valgrind: Disable Power ISA 2.07 check

The Power ISA 2.07 check fails when not supported by both machine 
architecture and gcc.

Upstream-Status: Inappropriate [disable feature]

Signed-off-by: Gabriel Barbu <gabriel.barbu@enea.com>

--- a/configure.ac	2014-05-05 17:06:29.674630565 +0200
+++ b/configure.ac	2014-05-06 13:16:47.525598513 +0200
@@ -1316,18 +1316,25 @@
 AM_CONDITIONAL(BUILD_DFP_TESTS, test x$ac_gcc_have_dfp_type = xyes)
 
 # isa 2.07 checking
-AC_MSG_CHECKING([that assembler knows ISA 2.07 ])
+AC_ARG_ENABLE([isa_2_07_check],
+   [AS_HELP_STRING([--disable-isa_2_07_check],
+      [disable Power ISA 2.07 check])],
+      [],
+      [disable_isa_2_07_check=no])
 
-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
-]], [[
-  __asm__ __volatile__("mtvsrd 1,2 ");
-]])], [
-ac_asm_have_isa_2_07=yes
-AC_MSG_RESULT([yes])
-], [
-ac_asm_have_isa_2_07=no
-AC_MSG_RESULT([no])
-])
+AS_IF([test "x$disable_isa_2_07_check" = xno],
+   [AC_MSG_CHECKING([that assembler knows ISA 2.07 ])
+
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+   ]], [[
+     __asm__ __volatile__("mtvsrd 1,2 ");
+   ]])], [
+   ac_asm_have_isa_2_07=yes
+   AC_MSG_RESULT([yes])
+   ], [
+   ac_asm_have_isa_2_07=no
+   AC_MSG_RESULT([no])
+   ])])
 
 AM_CONDITIONAL(HAS_ISA_2_07, test x$ac_asm_have_isa_2_07 = xyes)