Add cc-compat.h - C compiler compat macros for internal use

Holds things such as FLEX_ARRAY and whatnot.

Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

src/cc-compat.h

+/*
+ * cc-compat.h - C compiler compat macros for internal use
+ */
+#ifndef INCLUDE_compat_h__
+#define INCLUDE_compat_h__
+
+/*
+ * See if our compiler is known to support flexible array members.
+ */
+#ifndef FLEX_ARRAY
+# if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
+#  define FLEX_ARRAY /* empty */
+# elif defined(__GNUC__)
+#  if (__GNUC__ >= 3)
+#   define FLEX_ARRAY /* empty */
+#  else
+#   define FLEX_ARRAY 0 /* older GNU extension */
+#  endif
+# endif
+
+/* Default to safer but a bit wasteful traditional style */
+# ifndef GIT_FLEX_ARRAY
+#  define GIT_FLEX_ARRAY 1
+# endif
+#endif
+
+#ifdef __GNUC__
+# define TYPEOF(x) (__typeof__(x))
+#else
+# define TYPEOF(x)
+#endif
+
+#endif /* INCLUDE_compat_h__ */