Merge #17466: depends: qt: Fix C{,XX} pickup

bc728d1 depends: qt: Fix C{,XX} pickup (Carl Dong)

Pull request description:

  QT LOVES to do things its own way and simply ignore all environment variables. Even listing `QMAKE_CC=...` in `./configure` flags does't work reliably. This is why we gotta literally edit their config files for them. Thanks QT.

ACKs for top commit:
  laanwj:
    ACK bc728d1

Tree-SHA512: 3d6a0535174d70937d11b8f44ac2ab720870345a2d5a541c3e0181163ffa1988ab4f934788e9c841b646d6f53c6dc51a4fe39b294dd042c38976091c0fb96c96

Author: laanwj

depends/packages/qt.mk

@@ -202,6 +202,8 @@ define $(package)_preprocess_cmds
   sed -i.old "s|QMAKE_CFLAGS           += |!host_build: QMAKE_CFLAGS            = $($(package)_cflags) $($(package)_cppflags) |" qtbase/mkspecs/win32-g++/qmake.conf && \
   sed -i.old "s|QMAKE_CXXFLAGS         += |!host_build: QMAKE_CXXFLAGS            = $($(package)_cxxflags) $($(package)_cppflags) |" qtbase/mkspecs/win32-g++/qmake.conf && \
   sed -i.old "0,/^QMAKE_LFLAGS_/s|^QMAKE_LFLAGS_|!host_build: QMAKE_LFLAGS            = $($(package)_ldflags)\n&|" qtbase/mkspecs/win32-g++/qmake.conf && \
+  sed -i.old "s|QMAKE_CC                = clang|QMAKE_CC                = $($(package)_cc)|" qtbase/mkspecs/common/clang.conf && \
+  sed -i.old "s|QMAKE_CXX               = clang++|QMAKE_CXX               = $($(package)_cxx)|" qtbase/mkspecs/common/clang.conf && \
   sed -i.old "s/LIBRARY_PATH/(CROSS_)?\0/g" qtbase/mkspecs/features/toolchain.prf
 endef