[PATCH GCC]Fix broken Canadian when checking isl library support

[Bin Cheng]

Hi,
Canadian build of arm/aarch64 (and other targets) toolchains are broken
because of isl library check.  There is below code in top level gcc
configuration.

    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for version 0.12 of
ISL" >&5
$as_echo_n "checking for version 0.12 of ISL... " >&6; }
    if test "$cross_compiling" = yes; then :
  gcc_cv_isl=yes
else
  cat confdefs.h - <<_ACEOF >conftest.$ac_ext

For Canadian build, corss_compiling is set to `yes', then gcc_cv_isl is set
to `yes' accordingly, no matter whether isl library is available or not.
We also can't set it to `no' by default, because "--with-isl=xxxx" option
would be nullified in this way.  I think the best we can do here is add
AC_LINK_IFELSE when checking.

This patch fixes the issue.

Is it OK?

2014-08-21  Bin Cheng  <bin.ch...@arm.com>

        * config/isl.m4 (ISL_CHECK_VERSION): Check link of isl library
        for cross_compiling.
        * configure: Regenerated.

Index: config/isl.m4
===================================================================
--- config/isl.m4       (revision 214255)
+++ config/isl.m4       (working copy)
@@ -122,7 +122,11 @@ AC_DEFUN([ISL_CHECK_VERSION],
     AC_RUN_IFELSE([_ISL_CHECK_CT_PROG($1,$2)],
        [gcc_cv_isl=yes],
        [gcc_cv_isl=no],
-       [gcc_cv_isl=yes])
+       [
+         AC_LINK_IFELSE([_ISL_CHECK_CT_PROG($1,$2)],
+             [gcc_cv_isl=yes],
+             [gcc_cv_isl=no])
+       ])
     AC_MSG_RESULT([$gcc_cv_isl])
 
     CFLAGS=$_isl_saved_CFLAGS
Index: configure
===================================================================
--- configure   (revision 214255)
+++ configure   (working copy)
@@ -5907,8 +5907,30 @@ $as_echo "$as_me: WARNING: using in-tree ISL, disa
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking for version 0.12 of ISL" 
>&5
 $as_echo_n "checking for version 0.12 of ISL... " >&6; }
     if test "$cross_compiling" = yes; then :
+
+         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <isl/version.h>
+   #include <string.h>
+int
+main ()
+{
+if (strncmp (isl_version (), "isl-0.12", strlen ("isl-0.12")) != 0)
+     return 1;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
   gcc_cv_isl=yes
 else
+  gcc_cv_isl=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+
+else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <isl/version.h>