configure.ac: Check for grep with AC_PROG_GREP

Perhaps with a new version of autoconf, I began seeing:

| checking the name lister (/usr/bin/nm -B) interface... ./configure: line 6973: External.*some_variable: command not found
| BSD nm

This is because AC_PROG_NM expands to

	...
	if $GREP 'External.*some_variable' conftest.out > /dev/null; then
	    lt_cv_nm_interface="MS dumpbin"
	fi
	...

I'm not sure if it's a bug in AC_PROG_NM that it doesn't call
AC_PROG_GREP, but it's easy enough for us to do it.

diff --git a/configure.ac b/configure.ac
index c0fbfe94135a63e83f9b71a9e84fa503d3effaf7..4bb89607e2d098768dc0a7c9946b0a08ae388b14 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -119,6 +119,7 @@ dnl other CC/CXX flags related help
 AC_ARG_VAR([CXX11_CXXFLAGS], [Compiler flag to enable C++11 support (only needed if not
                               enabled by default and different  from -std=c++11)])
 AM_PROG_CC_C_O
+AC_PROG_GREP
 AC_PROG_NM
 AM_PROG_AS
 AX_CHECK_GNU_MAKE