build: allow configuring path to binutils's nm tool during build

`nm` is used by "tools/create-exports-NetworkManager.sh" script.
Alloc configuring an explicit path during configure.

  BINUTILS_NM=/usr/bin/nm ./configure

Makefile.am

@@ -1478,7 +1478,7 @@ src_libNetworkManagerTest_la_LIBADD = \
 ###############################################################################
 
 src/NetworkManager.ver: src/libNetworkManager.la $(core_plugins)
-	$(AM_V_GEN) "$(srcdir)/tools/create-exports-NetworkManager.sh" --called-from-make "$(srcdir)"
+	$(AM_V_GEN) BINUTILS_NM="$(BINUTILS_NM)" "$(srcdir)/tools/create-exports-NetworkManager.sh" --called-from-make "$(srcdir)"
 
 CLEANFILES += src/NetworkManager.ver
 

configure.ac

@@ -1121,6 +1121,8 @@ AM_PATH_PYTHON([], [], [PYTHON=python])
 AC_SUBST(PYTHON, [$PYTHON])
 AC_DEFINE_UNQUOTED(TEST_NM_PYTHON, "$PYTHON", [Define python path for test binary])
 
+AC_PATH_TOOL(BINUTILS_NM, nm, nm)
+
 # check if we can build setting property documentation
 build_setting_docs=no
 if test -n "$INTROSPECTION_MAKEFILE"; then

tools/create-exports-NetworkManager.sh

@@ -29,7 +29,7 @@ _sort() {
 }
 
 call_nm() {
-    nm "$1" |
+    "${BINUTILS_NM:-${NM:-nm}}" "$1" |
         sed -n 's/.* \([^ ]\) \([^ ]*\)$/\1 \2/p'
 }