Manpages of mingw64-gcc

• x86_64-w64-mingw32-gcc(1)
• x86_64-w64-mingw32-gcov-dump(1)
• x86_64-w64-mingw32-gcov-tool(1)
• x86_64-w64-mingw32-gcov(1)
• x86_64-w64-mingw32-lto-dump(1)