Do not include stdlib.h and string.h, config.h does it.

Do not include stdlib.h and string.h, config.h does it.
* src/xfont.c:
* src/w32term.c:
* src/w32reg.c:
* src/w32inevt.c:
* src/w32heap.c:
* src/w32console.c:
* src/w16select.c:
* src/unexsol.c:
* src/term.c:
* src/sound.c:
* src/scroll.c (m):
* src/gtkutil.c:
* src/font.c:
* src/filelock.c:
* src/fileio.c:
* src/dosfns.c:
* src/dbusbind.c:
* src/bidi.c:
* src/callproc.c:
* src/process.c:
* src/msdos.c:
* src/charset.c: Do not include stdlib.h and string.h, config.h does it.

* configure.in: Include stdlib.h and string.h unconditionally.