Reintroduce C++ support and add usage tests for C++ (#4)

Reviewed-on: #4
Co-authored-by: Abdelrahman <said.abdelrahman89@gmail.com>
Co-committed-by: Abdelrahman <said.abdelrahman89@gmail.com>

src/core/os/cpath/cpath.h

@@ -8,6 +8,10 @@
 #include "../../../primitives/mem_allocator/mem_allocator.h"
 #include "../../../primitives/strings/str8/str8.h"
 
+#ifdef WAPP_PLATFORM_CPP
+BEGIN_C_LINKAGE
+#endif // !WAPP_PLATFORM_CPP
+
 #ifdef WAPP_PLATFORM_POSIX
 #define PATH_SEP '/'
 #elif defined(WAPP_PLATFORM_WINDOWS)
@@ -29,4 +33,8 @@ enum {
 u32  wapp_cpath_join_path(Str8 *dst, const Str8List *parts);
 Str8 *dirup(const Allocator *allocator, Str8RO *path, u64 levels);
 
+#ifdef WAPP_PLATFORM_CPP
+END_C_LINKAGE
+#endif // !WAPP_PLATFORM_CPP
+
 #endif // !CPATH_H