Add the proper handling of the RC_FILE variable in qmake project files.

[dmik]

It will be useful to teach the qmake utility to automatically compile and link OS/2 resource files to generated executables, using the RC_FILE project variable to specify a resource script file (like it does under Win32).

Currently, the GNUMAKE backend for qmake (used by Qt/OS2) handles this variable incorrectly, which needs to be fixed.

[dmik]

RC_FILE and RES_FILE qmake project variables are now correctly supported by the GNUMAKE qmake backend (changeset:66).

In order to bind OS/2 resources to a project's executable, one can now specify the name of the .rc file using the RC_FILE variable in the project file. The given .rc file will be automatically compiled when necessary (qmake.conf for GCC uses the standard OS/2 RC compiler, rc.exe, that must be located somewhere in the PATH) and then bound to the executable.

It's also possible to specify a precompiled resource file name using the RES_FILE project variable. In this case, the generated makefile will just bind the specified resource file to the project's executable every time it is rebuilt.

To support RC_FILE and RES_FILE functionality, two new internal qmake variables are recognized by the GNUMAKE backend: QMAKE_RUN_RC_RES and QMAKE_RUN_RC_EXE. See ​http://svn.netlabs.org/repos/qt3/trunk/os2-doc/doc.html#GNUMAKE for more info.