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/uuid/uuid.h

@@ -7,6 +7,10 @@
 #include "../common/platform/platform.h"
 #include "../primitives/strings/str8/str8.h"
 
+#ifdef WAPP_PLATFORM_CPP
+BEGIN_C_LINKAGE
+#endif // !WAPP_PLATFORM_CPP
+
 #define UUID_BUF_LENGTH 48
 #define WAPP_UUID_SPEC WAPP_STR8_SPEC
 #define wapp_uuid_varg(UUID) wapp_str8_varg((UUID).uuid)
@@ -26,4 +30,8 @@ struct uuid {
 // Fails when passed a NULL pointer.
 UUID *wapp_uuid_init_uuid4(UUID *uuid);
 
+#ifdef WAPP_PLATFORM_CPP
+END_C_LINKAGE
+#endif // !WAPP_PLATFORM_CPP
+
 #endif // !UUID_H