Remove configure test for needing -P for .S files.

There is a configure test for "whether we need to use -P to assemble
.S files".

I think this test is long obsolete.  I don't have a specific reference
to a binutils change or version that obsoleted this test, but: (a) we
only support GNU binutils; (b) it looks like every architecture
supported by glibc has '#' as a line comment character in its gas
port; (c) in any case, if the (compiler, assembler) combination in use
cannot compile a .S file without special options, that would clearly
be a substantially broken combination, which I don't think we need to
allow for at all.

The test in question was added by:

Thu Jan 27 16:46:03 1994  Roland McGrath  (roland@churchy.gnu.ai.mit.edu)

        * configure.in (asm-CPPFLAGS): Add new check to see if assembling
        a .S file loses without -P.  If so, set asm-CPPFLAGS=-P in config.make.

This patch removes the test and the reference to this issue in the
comment on the default empty definition of asm-CPPFLAGS.  (Various
other settings of asm-CPPFLAGS remain in sysdeps Makefile fragments.)

Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).

	* configure.ac (libc_cv_need_minus_P): Remove configure test.
	* configure: Regenerated.
	* Makeconfig (asm-CPPFLAGS): Remove reference to -P in comment.