title: QMAKE_EXTRA_COMPILERS dependencies issue
body: <p>All</p>
  
  <p>I have Qt project which contains <strong>.ts-file</strong> and <strong>.qrc-file</strong> containing reference to generated <strong>.qm-file</strong>. We do not store .qm-files in our version control system. The issue here is that when I check out source code and run "make", I'm getting error </p>
  
  <pre><code>RCC: Error in 'CoreGeneral.qrc': Cannot find file 'core.general_en.qm'
  </code></pre>
  
  <p>I created updateqm.pri files to get .qm files generated before build, this file I include to my .pro files</p>
  
  <pre><code>!contains(QMAKE_EXTRA_COMPILERS, updateqm) {
      updateqm.input         = TRANSLATIONS
      updateqm.output        = ${QMAKE_FILE_BASE}.qm
      updateqm.commands      = $$[QT_INSTALL_BINS]/lrelease -idbased ${QMAKE_FILE_IN} -qm ${QMAKE_FILE_BASE}.qm
      updateqm.CONFIG       += no_link target_predeps
      QMAKE_EXTRA_COMPILERS += updateqm
      PRE_TARGETDEPS        += compiler_updateqm_make_all }
  </code></pre>
  
  <p>But again, I'm getting this error, though .qm files eventually get generated.
  Compile output looks like this</p>
  
  <pre><code> C:\Qt\Qt5.2.1\5.2.1\msvc2012\bin\lrelease -idbased core.general_en.ts -qm core.general_en.qm
      C:\Qt\Qt5.2.1\5.2.1\msvc2012\bin\uic.exe PSGHTMLDisplay.ui -o GeneratedFiles\ui_PSGHTMLDisplay.h
      C:\Qt\Qt5.2.1\5.2.1\msvc2012\bin\rcc.exe -name CoreGeneral CoreGeneral.qrc -o GeneratedFiles\qrc_CoreGeneral.cpp
  RCC: Error in 'CoreGeneral.qrc': Cannot find file 'core.general_en.qm'
  
  Updating 'core.general_en.qm'...
      Generated 108 translation(s) (0 finished and 108 unfinished)
  </code></pre>
  
  <p>So, for me it looks like RCC starts processing .qrc file before lrelease finished generating .qm-files.</p>
  
  <p>Is there any approach to avoid this issue?</p>
  
  <p><strong>P.S.</strong> I tried using QMAKE_EXTRA_TARGETS to create pre-build event that will be generating .qm-files before any other target will be started but it didn't work for me. I used approach described here <a href="http://blog.mgsxx.com/?p=2180" rel="nofollow">enter link description here</a></p>
  
  <p>Briefly, the approach of creating pre-build event is like below</p>
  
  <pre><code>    # создаем файл-заглушку
  !exists($$OUT_PWD/.beforebuild) {
    system(@echo aaa &gt; $$system_path($${OUT_PWD}/.beforebuild))
  }
  
  QMAKE_EXTRA_TARGETS += before_build makefilehook
  
  makefilehook.target = $(MAKEFILE)
  makefilehook.depends = .beforebuild
  
  POST_TARGETDEPS += .beforebuild
  
  before_build.target = .beforebuild
  before_build.depends = FORCE
  before_build.commands = @echo our command
  </code></pre>