3rdParty: build mupen64plus-core with VULKAN=0

RMG overrides the video extension functions anyways,
so we don't need to have vulkan support in the default
video extension implementation, which just adds an
unneeded dependency in some cases

Source/3rdParty/CMakeLists.txt

@@ -71,7 +71,7 @@ ExternalProject_Add(mupen64plus-core
     BUILD_COMMAND ${MAKE_CMD} all -f ${M64P_CORE_DIR}/projects/unix/Makefile 
         SRCDIR=${CMAKE_CURRENT_SOURCE_DIR}/mupen64plus-core/src 
         SUBDIR=${CMAKE_CURRENT_SOURCE_DIR}/mupen64plus-core/subprojects 
-        OSD=0 NEW_DYNAREC=1 NO_ASM=$<BOOL:${NO_ASM}> KEYBINDINGS=0 ACCURATE_FPU=1
+        OSD=0 NEW_DYNAREC=1 NO_ASM=$<BOOL:${NO_ASM}> KEYBINDINGS=0 ACCURATE_FPU=1 VULKAN=0
         TARGET=${CORE_FILE} DEBUG=${MAKE_DEBUG}
         CC=${MAKE_CC_COMPILER} CXX=${MAKE_CXX_COMPILER}
         OPTFLAGS=${MAKE_OPTFLAGS}