build-sys: fix build on compilers without static_assert

Build would fail when assert was used on the same line in
different files #included together.

https://bugs.freedesktop.org/show_bug.cgi?id=87339

src/shared/macro.h

@@ -238,7 +238,7 @@ static inline unsigned long ALIGN_POWER2(unsigned long u) {
 #else
 #define assert_cc(expr)                                                 \
         DISABLE_WARNING_DECLARATION_AFTER_STATEMENT;                    \
-        struct CONCATENATE(_assert_struct_, __LINE__) {                 \
+        struct CONCATENATE(_assert_struct_, __COUNTER__) {              \
                 char x[(expr) ? 0 : -1];                                \
         };                                                              \
         REENABLE_WARNING