re PR c/25892 (-Wpointer-sign creates problems for Emacs)

gcc/ChangeLog:
PR c/25892
* c.opt (Wpointer-sign): Init to -1.
* c-opts.c (c_common_handle_option): Set to 1 on OPT_Wall and
OPT_pedantic, to 0 otherwise.
* doc/invoke.texi: Update.
gcc/testsuite/ChangeLog:
PR c/25892
* gcc.dg/Wpointer-sign.c: New.
* gcc.dg/Wpointer-sign-Wall.c: New.
* gcc.dg/Wpointer-sign-Wall-no.c: New.
* gcc.dg/Wpointer-sign-pedantic.c: New.
* gcc.dg/Wpointer-sign-pedantic-no.c: New.
* gcc.dg/conv-2.c: Use -Wpointer-sign.

From-SVN: r110265