in the same executable without collision (c-exp.y, m2-exp.y). Add forward
delaration of function returning pointer to shut up compiler warnings about
conversion of int to pointer (symtab.h).
* expread.y, expread.tab.c: Remove.
* parser-defs.h: New file with common declarations from expread.y.
* c-exp.y: New file with the C parser from expread.y.
* m2-exp.y: New file with the Modula-2 parser.