Drop WLR_VERSION_API_*
These weren't set in the build, thus Meson was just dropping them
in the generated file.
#define WLR_VERSION_NUM ((WLR_VERSION_MAJOR << 16) | (WLR_VERSION_MINOR << 8) | WLR_VERSION_MICRO)
-#mesondefine WLR_VERSION_API_CURRENT
-#mesondefine WLR_VERSION_API_REVISION
-#mesondefine WLR_VERSION_API_AGE
-
#endif
