Pullup ticket #5927 - requested by markd
x11/qt5-qtbase: build fix

Revisions pulled up:
- x11/qt5-qtbase/Makefile                                      1.74
- x11/qt5-qtbase/files/qmake.conf                              1.9

---
  Module Name: pkgsrc
  Committed By: markd
  Date: Mon Apr  1 19:58:51 UTC 2019

  Modified Files:
  pkgsrc/x11/qt5-qtbase: Makefile
  pkgsrc/x11/qt5-qtbase/files: qmake.conf

  Log Message:
  qt5-qtbase: fix setting QMAKE_COMPILER

  QMAKE_COMPILER is meant to signify the compiler family being used
        gcc              for gcc
        gcc clang llvm  for clang
  should properly fix the build issue seen on CentOS and likely other
  systems.

(bsiegert)