* configure: Automatically test for `gmake' also.

Suggested by Mojca Miklavec <mojca.miklavec.lists@gmail.com>.
diff --git a/configure b/configure
index 5052c08..b0c6d53 100755
--- a/configure
+++ b/configure
@@ -18,24 +18,26 @@
 # respect GNUMAKE environment variable for backwards compatibility
 if test "x$GNUMAKE" = x; then
   if test "x$MAKE" = x; then
-    MAKE=make
+    if test "x`make -v 2>/dev/null | grep '\(GNU\|makepp\)'`" = x; then
+      MAKE=gmake
+    else
+      MAKE=make
+    fi
   fi
 else
   MAKE=$GNUMAKE
 fi
 
-if test -z "`$MAKE -v 2>/dev/null | grep GNU`"; then
-  if test -z "`$MAKE -v 2>/dev/null | grep makepp`"; then
-    echo "GNU make (>= 3.80) or makepp (>= 1.19) is required to build FreeType2." >&2
-    echo "Please try" >&2
-    echo >&2
-    echo "  MAKE=<GNU make command name> $0" >&2
-    echo >&2
-    echo "or" >&2
-    echo >&2
-    echo "  MAKE=\"makepp --norc-substitution\" $0" >&2
-    exit 1
-  fi
+if test "x`$MAKE -v 2>/dev/null | grep '\(GNU\|makepp\)'`" = x; then
+  echo "GNU make (>= 3.80) or makepp (>= 1.19) is required to build FreeType2." >&2
+  echo "Please try" >&2
+  echo >&2
+  echo "  MAKE=<GNU make command name> $0" >&2
+  echo >&2
+  echo "or" >&2
+  echo >&2
+  echo "  MAKE=\"makepp --norc-substitution\" $0" >&2
+  exit 1
 fi
 
 # Get `dirname' functionality.  This is taken and adapted from autoconf's