buildenv/1.2.x/win32: generate libsndfile-1.lib from the DLL instead of using the MinGW-GCC-generated import lib.
buildenv/1.2.x/win32: generate libsndfile-1.lib from the DLL instead of using the MinGW-GCC-generated import lib.

ccpgames/mumble-releng,ccpgames/mumble-releng