Added emx/gcc support on OS/2.
* Makefile: Added appropriate section for initial build
* fileos2.c: Added necessary #include and #define directives
* Jambase: Modified OS/2 sections to allow both Watcom or emx/gcc
* jambase.c: Generated by mkjambase from new Jambase file
* Jambase.html: Adapted to document EMXGCC variable used on OS/2