Fix MIPS assembly code to work with newer GCC, where the "=h"
constraint is no longer supported.

--- libmad/fixed.h.orig	2004-02-16 21:02:03.000000000 -0500
+++ libmad/fixed.h	2011-10-29 18:47:21.000000000 -0400
@@ -304,8 +304,8 @@
  * significant bit depends on OPT_ACCURACY via mad_f_scale64().
  */
 #  define MAD_F_MLX(hi, lo, x, y)  \
-    asm ("mult	%2,%3"  \
-	 : "=l" (lo), "=h" (hi)  \
+    asm ("mult	%2,%3\n\tmfhi  %1"  \
+	 : "=l" (lo), "=r" (hi)  \
 	 : "%r" (x), "r" (y))
 
 # if defined(HAVE_MADD_ASM)
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<tr><td><span title='2017-03-30 22:59:53 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/pth.scm?id=84157bb8bf2c610584e0836047da4c710f8eaf76'>Merge branch 'master' into core-updates</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-03-30 01:30:16 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/pth.scm?id=6fd52309b8f52c9bb59fccffac53e029ce94b698'>gnu: Use HTTPS for almost all gnu.org HOME-PAGEs.</a></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-03-02 11:51:43 +0200'>2017-03-02</span></td><td><a href='/guix/commit/gnu/packages/pth.scm?id=10045e5c81b6dfcf3804ceb1bb4b8df04bde7c98'>gnu: pth: Add support for aarch64.</a></td><td>Efraim Flashner</td></tr>