Merge commit '38434a9f'

* commit '38434a9f':
  configure: Simplify restrict keyword handling
Merged-by: James Almer <jamrial@gmail.com>

configure

@@ -5307,9 +5307,8 @@ extern_prefix=${sym%%ff_extern*}
 
 ! disabled inline_asm && check_inline_asm inline_asm '"" ::'
 
-_restrict=
-for restrict_keyword in restrict __restrict__ __restrict; do
-    check_cc <<EOF && _restrict=$restrict_keyword && break
+for restrict_keyword in restrict __restrict__ __restrict ""; do
+    check_cc <<EOF && break
 void foo(char * $restrict_keyword p);
 EOF
 done
@@ -6495,9 +6494,9 @@ elif enabled_any msvc icl; then
     # MSVC 2013 and newer can handle it fine.
     # If this declspec fails, force including stdlib.h before the restrict redefinition
     # happens in config.h.
-    if [ $_restrict != restrict ]; then
+    if [ $restrict_keyword != restrict ]; then
         check_cc <<EOF || add_cflags -FIstdlib.h
-__declspec($_restrict) void* foo(int);
+__declspec($restrict_keyword) void *foo(int);
 EOF
     fi
     # the new SSA optimzer in VS2015 U3 is mis-optimizing some parts of the code
@@ -6972,7 +6971,7 @@ cat > $TMPH <<EOF
 #define FFMPEG_DATADIR "$(eval c_escape $datadir)"
 #define AVCONV_DATADIR "$(eval c_escape $datadir)"
 #define CC_IDENT "$(c_escape ${cc_ident:-Unknown compiler})"
-#define av_restrict $_restrict
+#define av_restrict $restrict_keyword
 #define EXTERN_PREFIX "${extern_prefix}"
 #define EXTERN_ASM ${extern_prefix}
 #define BUILDSUF "$build_suffix"