Build fails on MInGW-w64 because of cdbext changes

this is regression, 4.13.0 do not have this issue. error is

```

mingw32-make -f Makefile.Release
mingw32-make[4]: Entering directory 'Q:/qtc-4.13.1/src/libs/qtcreatorcdbext'
g++ -c -fno-keep-inline-dllexport -Wno-noexcept-type -O2 -MT -std=gnu+1y -Wall -Wextra -Wextra -fexceptions -mthreads -DUNICODE -D_UNICODE -DWIN32 -DMINGW_HAS_SECURE_API=1 -D"RELATIVE_PLUGIN_PATH=\"../lib/qtcreator/plugins\"" -D"RELATIVE_LIBEXEC_PATH=\".\"" -D"RELATIVE_DATA_PATH=\"../share/qtcreator\"" -D"RELATIVE_DOC_PATH=\"../share/doc/qtcreator\"" -DIDE_LIBRARY_BASENAME=\"lib\" -DQT_CREATOR -DQT_NO_JAVA_STYLE_ITERATORS -DQT_NO_CAST_TO_ASCII -DQT_RESTRICTED_CAST_FROM_ASCII -DQT_DISABLE_DEPRECATED_BEFORE=0x050900 -DQT_USE_FAST_OPERATOR_PLUS -DQT_USE_FAST_CONCATENATION -I..\..\..\src -I..\..\..\src -I..\..\libs -IQ:/qtc-4.13.1/tools -I..\..\plugins -I..\..\libs -I..\3rdparty -IQ:\qt-5.15.1\mkspecs\win32-g+ -o release\qtcreatorcdbextension.o qtcreatorcdbextension.cpp
cc1plus.exe: error: to generate dependencies you must specify either '-M' or '-MM'
mingw32-make[4]: *** [Makefile.Release:156: release/qtcreatorcdbextension.o] Error 1
mingw32-make[4]: Leaving directory 'Q:/qtc-4.13.1/src/libs/qtcreatorcdbext'
mingw32-make[3]: *** [Makefile:45: release] Error 2
mingw32-make[3]: Leaving directory 'Q:/qtc-4.13.1/src/libs/qtcreatorcdbext'
mingw32-make[2]: *** [Makefile:1198: sub-qtcreatorcdbext-release] Error 2
mingw32-make[2]: Leaving directory 'Q:/qtc-4.13.1/src/libs'
mingw32-make[1]: *** [Makefile:798: sub-libs-release_ordered] Error 2
mingw32-make[1]: Leaving directory 'Q:/qtc-4.13.1/src'
mingw32-make: *** [Makefile:614: sub-src-release_ordered] Error 2

```

this -MT is VS switch not GCC