Fix strchr for basic non-sse case on x86

Fix source location. Move declaration of __strchr_chk out of
ifdef __BIONIC_FORTIFY which should be available for strchr.cpp
compilation when __BIONIC_FORTIFY is not defined.

Change-Id: I552a6e16656e59b276b322886cfbf57bbfb2e6a7
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>