Enhance/fix VMS setting of program name, MAKE/MAKE_COMMAND variables

* default.c, main.c, makeint.h, vmsfunctions.c: prefix argv[0] with
"mcr " for MAKE/MAKE_COMMAND and set the program name to the image
filename (without the .exe;version)
* vmsfunctions.c: remove obsolete code
* vmsify: use xmalloc
5 files changed