configure: Check if C99 "static" keyword is supported for array sizes.

configure.ac

@@ -1007,6 +1007,24 @@ if test $i_cv_signed_time_t = yes; then
   AC_DEFINE(TIME_T_SIGNED,, [Define if your time_t is signed])
 fi
 
+AC_CACHE_CHECK([if we can use C99 static in array sizes],i_cv_c99_static_arrays,[
+  AC_TRY_COMPILE([
+    void foo(int arr[static 20]);
+  ], [
+  ], [
+    i_cv_c99_static_arrays=yes
+  ], [
+    i_cv_c99_static_arrays=no
+  ])
+])
+
+if test $i_cv_c99_static_arrays = yes; then
+  static_value=static
+else
+  static_value=
+fi
+AC_DEFINE_UNQUOTED(STATIC_ARRAY, $static_value, [C99 static array])
+
 dnl Our implementation of AC_C_FLEXIBLE_ARRAY_MEMBER.
 dnl Use it until autoconf 2.61+ becomes more widely used
 AC_CACHE_CHECK([if we can use C99-like flexible array members],i_cv_c99_flex_arrays,[

src/lib/macros.h

@@ -227,9 +227,8 @@
 #endif
 
 #ifdef __cplusplus
+#  undef STATIC_ARRAY
 #  define STATIC_ARRAY
-#else
-#  define STATIC_ARRAY static
 #endif
 
 #endif