Make sure we check for egrep before we use it.

diff --git a/configure.ac b/configure.ac
index ef835ea..b9bb464 100644
--- a/configure.ac
+++ b/configure.ac
@@ -88,6 +88,7 @@
 AC_CHECK_TOOL(WINDRES,windres,false)
 AC_PROG_LN_S
 WINE_PROG_LN
+AC_PROG_EGREP
 AC_PATH_PROG(LDCONFIG, ldconfig, true, [/sbin /usr/sbin $PATH])
 AC_PROG_INSTALL
 dnl Prepend src dir to install path dir if it's a relative path