Sync isl.m4 with GCC tree

* isl.m4: Sync with GCC tree.

config/ChangeLog

@@ -1,3 +1,7 @@
+2015-03-16  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* isl.m4: Sync with GCC tree.
+
 2015-03-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	Sync with GCC

config/isl.m4

@@ -68,6 +68,8 @@ AC_DEFUN([ISL_INIT_FLAGS],
     ENABLE_ISL_CHECK=no
     AC_MSG_WARN([using in-tree ISL, disabling version check])
   fi
+
+  isllibs="${isllibs} -lisl"
 ]
 )
 
@@ -90,20 +92,9 @@ AC_DEFUN([ISL_REQUESTED],
 ]
 )
 
-# _ISL_CHECK_CT_PROG(MAJOR, MINOR)
-# --------------------------------------------
-# Helper for verifying ISL compile time version.
-m4_define([_ISL_CHECK_CT_PROG],[AC_LANG_PROGRAM(
-  [#include <isl/version.h>
-   #include <string.h>],
-  [if (strncmp (isl_version (), "isl-$1.$2", strlen ("isl-$1.$2")) != 0)
-     return 1;
-   ])])
-
-# ISL_CHECK_VERSION ISL_CHECK_VERSION (MAJOR, MINOR)
+# ISL_CHECK_VERSION ISL_CHECK_VERSION ()
 # ----------------------------------------------------------------
-# Test the found ISL to be exact of version MAJOR.MINOR and at least
-# REVISION.
+# Test that ISL contains functionality added to the minimum expected version.
 AC_DEFUN([ISL_CHECK_VERSION],
 [
   if test "${ENABLE_ISL_CHECK}" = yes ; then
@@ -115,11 +106,10 @@ AC_DEFUN([ISL_CHECK_VERSION],
     LDFLAGS="${_isl_saved_LDFLAGS} ${isllibs}"
     LIBS="${_isl_saved_LIBS} -lisl"
 
-    AC_MSG_CHECKING([for version $1.$2 of ISL])
-    AC_RUN_IFELSE([_ISL_CHECK_CT_PROG($1,$2)],
+    AC_MSG_CHECKING([for compatible ISL])
+    AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <isl/val.h>]], [[;]])],
 	[gcc_cv_isl=yes],
-	[gcc_cv_isl=no],
-	[gcc_cv_isl=yes])
+	[gcc_cv_isl=no])
     AC_MSG_RESULT([$gcc_cv_isl])
 
     CFLAGS=$_isl_saved_CFLAGS