use != '\0' comparison instead of SDL_strlen in the functions of SDL_getenv

src/stdlib/SDL_getenv.c

@@ -48,7 +48,7 @@ int
 SDL_setenv(const char *name, const char *value, int overwrite)
 {
     /* Input validation */
-    if (!name || SDL_strlen(name) == 0 || SDL_strchr(name, '=') != NULL || !value) {
+    if (!name || *name == '\0' || SDL_strchr(name, '=') != NULL || !value) {
         return (-1);
     }
     
@@ -59,7 +59,7 @@ int
 SDL_setenv(const char *name, const char *value, int overwrite)
 {
     /* Input validation */
-    if (!name || SDL_strlen(name) == 0 || SDL_strchr(name, '=') != NULL || !value) {
+    if (!name || *name == '\0' || SDL_strchr(name, '=') != NULL || !value) {
         return (-1);
     }
     
@@ -82,7 +82,7 @@ SDL_setenv(const char *name, const char *value, int overwrite)
     char *new_variable;
 
     /* Input validation */
-    if (!name || SDL_strlen(name) == 0 || SDL_strchr(name, '=') != NULL || !value) {
+    if (!name || *name == '\0' || SDL_strchr(name, '=') != NULL || !value) {
         return (-1);
     }
     
@@ -115,7 +115,7 @@ SDL_setenv(const char *name, const char *value, int overwrite)
     char *new_variable;
 
     /* Input validation */
-    if (!name || SDL_strlen(name) == 0 || SDL_strchr(name, '=') != NULL || !value) {
+    if (!name || *name == '\0' || SDL_strchr(name, '=') != NULL || !value) {
         return (-1);
     }
 
@@ -181,7 +181,7 @@ SDL_getenv(const char *name)
 #endif
 
     /* Input validation */
-    if (!name || !*name) {
+    if (!name || *name == '\0') {
         return NULL;
     }
 
@@ -194,7 +194,7 @@ SDL_getenv(const char *name)
     size_t bufferlen;
 
     /* Input validation */
-    if (!name || SDL_strlen(name)==0) {
+    if (!name || *name == '\0') {
         return NULL;
     }
     
@@ -222,7 +222,7 @@ SDL_getenv(const char *name)
     char *value;
 
     /* Input validation */
-    if (!name || SDL_strlen(name)==0) {
+    if (!name || *name == '\0') {
         return NULL;
     }