[REG 5.7->5.8] Qmake/VS generator: Multi-line post-build events broken in VS2015

Multi-line post-build events seem to be broken in Qt 5.9-beta4 with the qmake VS2015 project generator. The problem seem to be caused by missing newline characters. This breaks building of all ActiveQt server projects.

Steps to reproduce:

• cd qtactiveqt\examples\activeqt\simple
•  qmake -tp vc
• Open & build project in VS2015 (depends on QtAxServer, so you might need to build that project first).
• Observe failing post-build event.

  Error message:
   C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.CppCommon.targets(133,5): error MSB3075: The command "C:\Qt\5.9\msvc2015\bin\idc.exe "C:\Qt\subrepos\qtactiveqt\examples\activeqt\simple\debug\simpleax.dll" /idl .obj\debug\/simpleax.idl -version 1.0 midl .obj\debug\/simpleax.idl /nologo /tlb .obj\debug\/simpleax.tlb C:\Qt\5.9\msvc2015\bin\idc.exe "C:\Qt\subrepos\qtactiveqt\examples\activeqt\simple\debug\simpleax.dll" /tlb .obj\debug\/simpleax.tlb C:\Qt\5.9\msvc2015\bin\idc.exe "C:\Qt\subrepos\qtactiveqt\examples\activeqt\simple\debug\simpleax.dll" /regserver
   C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.CppCommon.targets(133,5): error MSB3075: :VCEnd" exited with code 5. Please verify that you have sufficient rights to run this command.
  

  Generated line 5.8

  D:\dev\5-vs15-58r\qt-58r\qtbase\bin\idc.exe
       "$(TargetPath)" /idl $(IntDir)/simpleax.idl -version
       1.0	 midl $(IntDir)/simpleax.idl /nologo /tlb
  

  vs 5.6:

  idc.exe "$(TargetPath)"
  /idl $(IntDir)simpleax.idl -version 1.0
if errorlevel 1 goto
  VCEnd
 midl $(IntDir)simpleax.idl /nologo /tlb
  $(IntDir)simpleax.tlb