Convert some prototypes to standard C.

Convert some prototypes to standard C.
* lib-src/make-docfile.c (xmalloc, xrealloc, concat, readline, fatal):
* lib-src/b2m.c (scan_file, scan_lisp_file, scan_c_file): Convert to
standard C prototypes.

* src/term.c (term_clear_mouse_face, Fidentity):
* src/syssignal.h (signal_handler_t):
* src/lisp.h (memory_warnings):
* src/coding.h (preferred_coding_system):
* src/cm.h (evalcost):
* src/blockinput.h (reinvoke_input_signal): Convert to standard C prototypes.