* configure: Use sed instead of grep.

This is more portable and consistent with `autogen.sh`.

configure

@@ -15,19 +15,10 @@
 
 rm -f config.mk builds/unix/unix-def.mk builds/unix/unix-cc.mk
 
-if test -z "$EGREP"; then
-  if echo a | grep -E '(a|b)' >/dev/null 2>&1; then
-    EGREP="grep -E"
-  else
-    # if grep -E doesn't work, assume egrep does.
-    EGREP=egrep
-  fi
-fi
-
 # respect GNUMAKE environment variable for backward compatibility
 if test "x$GNUMAKE" = x; then
   if test "x$MAKE" = x; then
-    if test "x`make -v 2>/dev/null | $EGREP 'GNU|makepp'`" = x; then
+    if test "x`make -v 2>/dev/null | sed -n -e '/GNU/p' -e '/makepp/p'`" = x; then
       MAKE=gmake
     else
       MAKE=make
@@ -37,7 +28,7 @@ else
   MAKE=$GNUMAKE
 fi
 
-if test "x`$MAKE -v 2>/dev/null | $EGREP 'GNU|makepp'`" = x; then
+if test "x`$MAKE -v 2>/dev/null | sed -n -e '/GNU/p' -e '/makepp/p'`" = x; then
   echo "GNU make (>= 3.81) or makepp (>= 2.0) is required to build FreeType2." >&2
   echo "Please try" >&2
   echo >&2