fpurge: migrate into <stdio.h> * lib/fpurge.h: Delete... * lib/stdio.in.h (fpurge): ...and declare here, instead. * lib/fpurge.c (fpurge): Change declaring header. * modules/fpurge (Files): Drop deleted file. (Depends-on): Add stdio. (configure.ac): Set witness. * modules/stdio (Makefile.am): Support fpurge macros. * m4/stdio_h.m4 (gl_STDIO_H_DEFAULTS): Likewise. * m4/fpurge.m4 (gl_FUNC_FPURGE): Set appropriate variables. * lib/fflush.c: Update client. * tests/test-fpurge.c: Likewise. * NEWS: Mention the change. Signed-off-by: Eric Blake <ebb9@byu.net>

# Suppress a valgrind message about use of uninitialized memory in strchrnul().
# This use is OK because it provides only a speedup.
{
    strchrnul-value4
    Memcheck:Value4
    fun:strchrnul
}
{
    strchrnul-value8
    Memcheck:Value8
    fun:strchrnul
}