build-scripts: modernized gcc-fat.sh for Big Sur and ARM64.

Put these in "clang-fat.sh" and "clang++-fat.sh" in case someone still needs
32-bit x86 support from the old scripts.

Fixes #4350.

build-scripts/clang++-fat.sh

@@ -0,0 +1,102 @@
+#!/bin/sh
+#
+# Build Universal binaries on Mac OS X, thanks Ryan!
+#
+# Usage: ./configure CXX="sh clang++-fat.sh" && make && rm -rf arm64 x64
+
+DEVELOPER="`xcode-select -print-path`/Platforms/MacOSX.platform/Developer"
+
+# Intel 64-bit compiler flags (10.6 runtime compatibility)
+CLANG_COMPILE_X64="clang++ -arch x86_64 -mmacosx-version-min=10.6 \
+-I/usr/local/include"
+
+CLANG_LINK_X64="-mmacosx-version-min=10.6"
+
+# ARM 64-bit compiler flags (11.0 runtime compatibility)
+CLANG_COMPILE_ARM64="clang++ -arch arm64 -mmacosx-version-min=11.0 \
+-I/usr/local/include"
+
+CLANG_LINK_ARM64="-mmacosx-version-min=11.0"
+
+
+# Output both Intel and ARM object files
+args="$*"
+compile=yes
+link=yes
+while test x$1 != x; do
+    case $1 in
+        --version) exec clang++ $1;;
+        -v) exec clang++ $1;;
+        -V) exec clang++ $1;;
+        -print-prog-name=*) exec clang++ $1;;
+        -print-search-dirs) exec clang++ $1;;
+        -E) CLANG_COMPILE_ARM64="$CLANG_COMPILE_ARM64 -E"
+            CLANG_COMPILE_X64="$CLANG_COMPILE_X64 -E"
+            compile=no; link=no;;
+        -c) link=no;;
+        -o) output=$2;;
+        *.c|*.cc|*.cpp|*.S|*.m|*.mm) source=$1;;
+    esac
+    shift
+done
+if test x$link = xyes; then
+    CLANG_COMPILE_ARM64="$CLANG_COMPILE_ARM64 $CLANG_LINK_ARM64"
+    CLANG_COMPILE_X64="$CLANG_COMPILE_X64 $CLANG_LINK_X64"
+fi
+if test x"$output" = x; then
+    if test x$link = xyes; then
+        output=a.out
+    elif test x$compile = xyes; then
+        output=`echo $source | sed -e 's|.*/||' -e 's|\(.*\)\.[^\.]*|\1|'`.o
+    fi
+fi
+
+# Compile ARM 64-bit
+if test x"$output" != x; then
+    dir=arm64/`dirname $output`
+    if test -d $dir; then
+        :
+    else
+        mkdir -p $dir
+    fi
+fi
+set -- $args
+while test x$1 != x; do
+    if test -f "arm64/$1" && test "$1" != "$output"; then
+        arm64_args="$arm64_args arm64/$1"
+    else
+        arm64_args="$arm64_args $1"
+    fi
+    shift
+done
+$CLANG_COMPILE_ARM64 $arm64_args || exit $?
+if test x"$output" != x; then
+    cp $output arm64/$output
+fi
+
+# Compile Intel 64-bit
+if test x"$output" != x; then
+    dir=x64/`dirname $output`
+    if test -d $dir; then
+        :
+    else
+        mkdir -p $dir
+    fi
+fi
+set -- $args
+while test x$1 != x; do
+    if test -f "x64/$1" && test "$1" != "$output"; then
+        x64_args="$x64_args x64/$1"
+    else
+        x64_args="$x64_args $1"
+    fi
+    shift
+done
+$CLANG_COMPILE_X64 $x64_args || exit $?
+if test x"$output" != x; then
+    cp $output x64/$output
+fi
+
+if test x"$output" != x; then
+    lipo -create -o $output arm64/$output x64/$output
+fi

build-scripts/clang-fat.sh

@@ -0,0 +1,105 @@
+#!/bin/sh
+#
+# Build Universal binaries on Mac OS X, thanks Ryan!
+#
+# Usage: ./configure CC="sh clang-fat.sh" && make && rm -rf arm64 x64
+
+DEVELOPER="`xcode-select -print-path`/Platforms/MacOSX.platform/Developer"
+
+# Intel 64-bit compiler flags (10.6 runtime compatibility)
+CLANG_COMPILE_X64="clang -arch x86_64 -mmacosx-version-min=10.6 \
+-DMAC_OS_X_VERSION_MIN_REQUIRED=1060 \
+-I/usr/local/include"
+
+CLANG_LINK_X64="-mmacosx-version-min=10.6"
+
+# ARM 64-bit compiler flags (11.0 runtime compatibility)
+CLANG_COMPILE_ARM64="clang -arch arm64 -mmacosx-version-min=11.0 \
+-I/usr/local/include"
+
+CLANG_LINK_ARM64="-mmacosx-version-min=11.0"
+
+
+# Output both Intel and ARM object files
+args="$*"
+compile=yes
+link=yes
+while test x$1 != x; do
+    case $1 in
+        --version) exec clang $1;;
+        -v) exec clang $1;;
+        -V) exec clang $1;;
+        -print-prog-name=*) exec clang $1;;
+        -print-search-dirs) exec clang $1;;
+        -E) CLANG_COMPILE_X64="$CLANG_COMPILE_X64 -E"
+            CLANG_COMPILE_ARM64="$CLANG_COMPILE_ARM64 -E"
+            compile=no; link=no;;
+        -c) link=no;;
+        -o) output=$2;;
+        *.c|*.cc|*.cpp|*.S|*.m|*.mm) source=$1;;
+    esac
+    shift
+done
+if test x$link = xyes; then
+    CLANG_COMPILE_X64="$CLANG_COMPILE_X64 $CLANG_LINK_X64"
+    CLANG_COMPILE_ARM64="$CLANG_COMPILE_ARM64 $CLANG_LINK_ARM64"
+fi
+if test x"$output" = x; then
+    if test x$link = xyes; then
+        output=a.out
+    elif test x$compile = xyes; then
+        output=`echo $source | sed -e 's|.*/||' -e 's|\(.*\)\.[^\.]*|\1|'`.o
+    fi
+fi
+
+# Compile Intel 64-bit
+if test x"$output" != x; then
+    dir=x64/`dirname $output`
+    if test -d $dir; then
+        :
+    else
+        mkdir -p $dir
+    fi
+fi
+set -- $args
+while test x$1 != x; do
+    if test -f "x64/$1" && test "$1" != "$output"; then
+        x64_args="$x64_args x64/$1"
+    else
+        x64_args="$x64_args $1"
+    fi
+    shift
+done
+$CLANG_COMPILE_X64 $x64_args || exit $?
+if test x"$output" != x; then
+    cp $output x64/$output
+fi
+
+# Compile ARM 64-bit
+if test x"$output" != x; then
+    dir=arm64/`dirname $output`
+    if test -d $dir; then
+        :
+    else
+        mkdir -p $dir
+    fi
+fi
+set -- $args
+while test x$1 != x; do
+    if test -f "arm64/$1" && test "$1" != "$output"; then
+        arm64_args="$arm64_args arm64/$1"
+    else
+        arm64_args="$arm64_args $1"
+    fi
+    shift
+done
+$CLANG_COMPILE_ARM64 $arm64_args || exit $?
+if test x"$output" != x; then
+    cp $output arm64/$output
+fi
+
+
+if test x"$output" != x; then
+    lipo -create -o $output arm64/$output x64/$output
+fi
+