Portability fixes for ./configure

Fix portability of ./configure by defaulting to a more generic POSIX
setup for all values of `uname -s` apart from "Darwin"

configure

@@ -4,7 +4,7 @@ OS=`uname -s`
 DEBUG=0
 PREFIX=/usr/local
 
-create_linux_config_h() {
+create_generic_config_h() {
     cat <<EOF > src/config.h
 #ifndef _CONFIG_H
 #define _CONFIG_H
@@ -55,7 +55,7 @@ CFLAGS		= $(CGFLAGS) $(CWFLAGS) $(COFLAGS)
 EOF
 }
 
-create_linux_build_mk() {
+create_generic_build_mk() {
     create_common_build_mk $@
 
     cat <<'EOF' >> mk/build.mk
@@ -106,13 +106,13 @@ if [ ! -d "mk" ]; then
 fi
 
 case $OS in
-    Linux)
-        create_linux_config_h
-		create_linux_build_mk
-    ;;
-
     Darwin)
         create_darwin_config_h
 		create_darwin_build_mk
     ;;
+
+    *)
+        create_generic_config_h
+		create_generic_build_mk
+    ;;
 esac