Add extern to three functions for gcc-10 compatibility.
Gbp-Pq: Name add-extern-qualifiers.patch
Revert "configure: Require libmodplug >= 0.8.9"
This reverts commit
48f014768dc22ecad23d0e9f53c38805a3aff832.
Gbp-Pq: Name 0002-Revert-configure-Require-libmodplug-0.8.9.patch