Add basic upper memory heap support for OS/2 32-bit platform.
Adds _use_os2_high_mem(), _os2hmalloc(), _os2lmalloc() 
to runtime.

[git-p4: depot-paths = "//depot/openwatcom/": change = 37516]
Enhance wlink for 32-bit OS/2 platform.
       Optionally generate IBM HLL debug data when available in object files.
Use upper memory when available to support linking
large applications such as Mozilla firefox.

[git-p4: depot-paths = "//depot/openwatcom/": change = 37517]