When building MAME I get this error:
make
GCC 4.9.2 detected
Compiling src/osd/modules/debugger/debugqt.cpp...
../../../../../src/osd/modules/debugger/debugqt.cpp:20:30: fatal error: QtWidgets/QApplication: No such file or directory
#include <QtWidgets/QApplication>
^
compilation terminated.
qtdbg_sdl.make:361: recipe for target '../../../../linux_gcc/obj/x64/Release/qtdbg_sdl/src/osd/modules/debugger/debugqt.o' failed
make[2]: *** [../../../../linux_gcc/obj/x64/Release/qtdbg_sdl/src/osd/modules/debugger/debugqt.o] Error 1
Makefile:16: recipe for target 'qtdbg_sdl' failed
make[1]: *** [qtdbg_sdl] Error 2
makefile:1003: recipe for target 'linux_x64' failed
make: *** [linux_x64] Error 2
How do I fix this error without a .pro file, because I can't find one anywhere.