ARM asm is armv7 only in wavpack. Restrict based on host cpu.
https://bugs.gentoo.org/show_bug.cgi?id=609168

Upstream PR:
https://github.com/dbry/WavPack/pull/20

Index: wavpack-5.1.0/configure.ac
===================================================================
--- wavpack-5.1.0.orig/configure.ac
+++ wavpack-5.1.0/configure.ac
@@ -159,7 +159,7 @@ AS_IF([test "x$enable_asm" != "xno"],[
   AS_CASE([$host_cpu],
     [i386|i486|i586|i686|i786], [AC_DEFINE([OPT_ASM_X86]) asm_selected=x86],
     [x86_64], [AC_DEFINE([OPT_ASM_X64]) asm_selected=x64],
-    [arm*], [AC_DEFINE([OPT_ASM_ARM]) asm_selected=arm],
+    [armv7*], [AC_DEFINE([OPT_ASM_ARM]) asm_selected=arm],
     [AS_IF([test "x$enable_asm" = "xyes"],[AC_MSG_ERROR(no assembly code for CPU $host_cpu)])]
   )
   AC_MSG_RESULT($asm_selected)