cpuinfo: updated xgetbv call for windows clang-cl.

from a patchset by Vladislav Dmitrievich Turbanov:
https://github.com/libsdl-org/SDL/pull/4062

src/cpuinfo/SDL_cpuinfo.c

@@ -289,7 +289,7 @@ CPU_calcCPUIDFeatures(void)
                 /* Check to make sure we can call xgetbv */
                 if (c & 0x08000000) {
                     /* Call xgetbv to see if YMM (etc) register state is saved */
-#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+#if (defined(__GNUC__) || defined(__llvm__)) && (defined(__i386__) || defined(__x86_64__))
                     __asm__(".byte 0x0f, 0x01, 0xd0" : "=a" (a) : "c" (0) : "%edx");
 #elif defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) && (_MSC_FULL_VER >= 160040219) /* VS2010 SP1 */
                     a = (int)_xgetbv(0);