* configure: Revert changes made on May 18 and May 19.
* Makefile.in (CC_FOR_TARGET): Make sure as/ld in the gcc
directory are used if they exist. Make sure
$(build_tooldir)/include is searched for header files,
$(build_tooldir)/lib/ for library files.
(GCC_FOR_TARGET): Likewise.
(CXX_FOR_TARGET): Likewise.
Add ``-W -Wall'' to sub-directories bfd, binutils, gas gprof, ld and
opcodes by the addition of WARN_CFLAGS to Makefile.am and configury to
set it. Add configure option --enable-build-warnings.
Re-generate all and sundry using auto*-000227.
