cleaned up header file mess in compiler sources

src/snc/gen_ss_code.c

src/snc/gen_ss_code.h

src/snc/gen_tables.c

src/snc/gen_tables.h

src/snc/parse.c

src/snc/parse.h

src/snc/parsedefs.h

src/snc/phase2.c

src/snc/phase2.h

src/snc/snc_main.c

src/snc/snc_main.h