tests: Consistently use <triple>-gcc instead of <triple>-clang for cross compilation

While <triple>-clang is more specific, using <triple>-gcc allows
testing GCC based toolchains (somewhat) with the same scripts/makefiles
too.

run-tests.sh

@@ -58,7 +58,7 @@ if ! $ANY_ARCH-w64-mingw32-gcc$TOOLEXT -E is-ucrt.c > /dev/null 2>&1; then
 fi
 rm -f is-ucrt.c
 
-if (echo "int main(){}" | $ANY_ARCH-w64-mingw32-clang$TOOLEXT -x c++ - -o has-cfguard-test.exe -mguard=cf); then
+if (echo "int main(){}" | $ANY_ARCH-w64-mingw32-gcc$TOOLEXT -x c++ - -o has-cfguard-test.exe -mguard=cf); then
     if llvm-readobj$TOOLEXT --coff-load-config has-cfguard-test.exe | grep -q 'CF_INSTRUMENTED (0x100)'; then
         HAVE_CFGUARD=1
     elif [ -n "$HAVE_CFGUARD" ]; then

test/Makefile

@@ -37,8 +37,8 @@ ifneq ($(ARCH),)
     CROSS = $(ARCH)-w64-mingw32-
     CROSS_UWP = $(ARCH)-w64-mingw32uwp-
 endif
-CC = $(CROSS)clang$(TOOLEXT)
-CXX = $(CROSS)clang++$(TOOLEXT)
+CC = $(CROSS)gcc$(TOOLEXT)
+CXX = $(CROSS)g++$(TOOLEXT)
 WIDL = $(CROSS)widl$(TOOLEXT)
 CC_UWP = $(CROSS_UWP)clang$(TOOLEXT)