musl: fixed m4 to cross-compile and to workaround gnulib weirdness

Note:

If you see something like this while trying to build a package using musl libc
this kind of fix might also apply for that package!

------------------------------------------------------------------------------
freadahead.c: In function 'freadahead':
freadahead.c:83:3: error: #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, th en report this to bug-gnulib."
------------------------------------------------------------------------------

base/musl/parse-config-9

@@ -79,6 +79,8 @@ if [ "$SDECFG_LIBC" == "musl" ]; then
 	musl_fix_gnulib() {
 		local dir="$1"
 
+		echo_status "fixing gnulib weirdness in $dir"
+
 		gl_config_cache="
 			gl_cv_func_isnanl_works=yes \
 			gl_cv_header_working_stdint_h=yes \
@@ -168,6 +170,12 @@ if [ "$SDECFG_LIBC" == "musl" ]; then
 	libtool)
 		hook_add preconf 9 'musl_findall_fix_configsub'
 		;;
+
+	# packages to fix gnulib weirdness
+	m4)
+		hook_add preconf 9 'musl_fix_gnulib lib'
+		;;	
+		
 	esac
 
 	# same package translations to look for patches

base/musl/pkg/m4/m4.conf

@@ -0,0 +1,19 @@
+# --- SDE-COPYRIGHT-NOTE-BEGIN ---
+# This copyright note is auto-generated by ./scripts/Create-CopyPatch.
+#
+# Filename: package/.../musl/pkg/m4/m4.conf
+# Copyright (C) 2013 The OpenSDE Project
+#
+# More information can be found in the files COPYING and README.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License. A copy of the
+# GNU General Public License can be found in the file COPYING.
+# --- SDE-COPYRIGHT-NOTE-END ---
+
+# avoid undefined reference to `rpl_fseeko' in `rpl_fflush'
+# by simply using the functions provided by the libc
+var_append CFLAGS ' ' "-Drpl_fflush=fflush"
+var_append CFLAGS ' ' "-Drpl_fseeko=fseeko"
+var_append configprefix ' ' 'CFLAGS=$CFLAGS'