test: Ignore clang warnings about C++ main definition

clang seems confused about whether main should be extern "C" or not.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

test/test-cplusplus.cpp

@@ -145,6 +145,12 @@
 #include <wctype.h>
 #include <wordexp.h>
 
+#ifdef __clang__
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wunknown-warning-option"
+#pragma GCC diagnostic ignored "-Wmain"
+#endif
+
 extern "C" {
 
 int main(void);