libtool.m4: fix the NM="/nm/over/here -B/option/with/path" case

My previous nm patch handled all cases but one -- if the user set NM in
the environment to a path which contained an option, libtool's nm
detection tries to run nm against a copy of nm with the options in it:
e.g. if NM was set to "nm --blargle", and nm was found in /usr/bin, the
test would try to run "/usr/bin/nm --blargle /usr/bin/nm --blargle".
This is unlikely to be desirable: in this case we should run
"/usr/bin/nm --blargle /usr/bin/nm".

Furthermore, as part of this nm has to detect when the passed-in $NM
contains a path, and in that case avoid doing a path search itself.
This too was thrown off if an option contained something that looked
like a path, e.g. NM="nm -B../prev-gcc"; libtool then tries to run
"nm -B../prev-gcc nm" which rarely works well (and indeed it looks
to see whether that nm exists, finds it doesn't, and wrongly concludes
that nm -p or whatever does not work).

Fix all of these by clipping all options (defined as everything
including and after the first " -") before deciding whether nm
contains a path (but not using the clipped value for anything else),
and then removing all options from the path-modified nm before
looking to see whether that nm existed.

NM=my-nm now does a path search and runs e.g.
  /usr/bin/my-nm -B /usr/bin/my-nm

NM=/usr/bin/my-nm now avoids a path search and runs e.g.
  /usr/bin/my-nm -B /usr/bin/my-nm

NM="my-nm -p../wombat" now does a path search and runs e.g.
  /usr/bin/my-nm -p../wombat -B /usr/bin/my-nm

NM="../prev-binutils/new-nm -B../prev-gcc" now avoids a path search:
  ../prev-binutils/my-nm -B../prev-gcc -B ../prev-binutils/my-nm

This seems to be all combinations, including those used by GCC bootstrap
(which, before this commit, fails to bootstrap when configured
--with-build-config=bootstrap-lto, because the lto plugin is now using
--export-symbols-regex, which requires libtool to find a working nm,
while also using -B../prev-gcc to point at the lto plugin associated
with the GCC just built.)

Regenerate all affected configure scripts.

	* libtool.m4 (LT_PATH_NM): Handle user-specified NM with
	options, including options containing paths.

binutils/configure

@@ -5273,25 +5273,31 @@ else
      lt_nm_to_check="$lt_nm_to_check nm"
    fi
  fi
- for lt_tmp_nm in $lt_nm_to_check; do
+ for lt_tmp_nm in "$lt_nm_to_check"; do
    lt_save_ifs="$IFS"; IFS=$PATH_SEPARATOR
    for ac_dir in $PATH /usr/ccs/bin/elf /usr/ccs/bin /usr/ucb /bin; do
      IFS="$lt_save_ifs"
      test -z "$ac_dir" && ac_dir=.
-     case "$lt_tmp_nm" in
+     # Strip out any user-provided options from the nm to test twice,
+     # the first time to test to see if nm (rather than its options) has
+     # an explicit path, the second time to yield a file which can be
+     # nm'ed itself.
+     tmp_nm_path="`$ECHO "$lt_tmp_nm" | sed 's, -.*$,,'`"
+     case "$tmp_nm_path" in
      */*|*\\*) tmp_nm="$lt_tmp_nm";;
      *) tmp_nm="$ac_dir/$lt_tmp_nm";;
      esac
-     if test -f "$tmp_nm" || test -f "$tmp_nm$ac_exeext" ; then
+     tmp_nm_to_nm="`$ECHO "$tmp_nm" | sed 's, -.*$,,'`"
+     if test -f "$tmp_nm_to_nm" || test -f "$tmp_nm_to_nm$ac_exeext" ; then
        # Check to see if the nm accepts a BSD-compat flag.
        # Adding the `sed 1q' prevents false positives on HP-UX, which says:
        #   nm: unknown option "B" ignored
-       case `"$tmp_nm" -B "$tmp_nm" 2>&1 | grep -v '^ *$' | sed '1q'` in
+       case `"$tmp_nm" -B "$tmp_nm_to_nm" 2>&1 | grep -v '^ *$' | sed '1q'` in
        *$tmp_nm*) lt_cv_path_NM="$tmp_nm -B"
 	 break
 	 ;;
        *)
-	 case `"$tmp_nm" -p "$tmp_nm" 2>&1 | grep -v '^ *$' | sed '1q'` in
+	 case `"$tmp_nm" -p "$tmp_nm_to_nm" 2>&1 | grep -v '^ *$' | sed '1q'` in
 	 *$tmp_nm*)
 	   lt_cv_path_NM="$tmp_nm -p"
 	   break
@@ -10981,7 +10987,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 10984 "configure"
+#line 10990 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11087,7 +11093,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11090 "configure"
+#line 11096 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H