[buddy] Adjust to support the Intel compiler (icc).

* configure.ac: Adjust to call...
    * m4/intel.m4: ...this new macro.

buddy/m4/intel.m4

@@ -0,0 +1,50 @@
+dnl Adapted from the predefined _AC_LANG_COMPILER_GNU.
+m4_define([_AC_LANG_COMPILER_INTEL],
+[AC_CACHE_CHECK([whether we are using the INTEL _AC_LANG compiler],
+		[ac_cv_[]_AC_LANG_ABBREV[]_compiler_intel],
+[
+_AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[#ifndef __INTEL_COMPILER
+       choke me
+#endif
+]])],
+		   [ac_compiler_intel=yes],
+		   [ac_compiler_intel=no])
+ac_cv_[]_AC_LANG_ABBREV[]_compiler_intel=$ac_compiler_intel
+])])# _AC_LANG_COMPILER_INTEL
+dnl The list of warnings that must be disabled.
+m4_define([_INTEL_IGNORE_WARNINGS],
+[ 522   dnl Remark ``redeclared "inline" after being called''
+  981   dnl Remark ``operands are evaluated in unspecified order''
+  383   dnl Remark ``value copied to temporary, reference to temporary used''
+  279   dnl Remark ``controlling expression is constant''
+]) # _INTEL_IGNORE_WARNINGS
+
+dnl Add extra flags when icc is used.
+AC_DEFUN([buddy_INTEL],
+[_AC_LANG_COMPILER_INTEL
+AC_CACHE_CHECK([to add extra CFLAGS for the INTEL C compiler],
+		[ac_cv_intel_cflags],
+[ dnl
+  if test x"$ac_compiler_intel" = x"yes"; then
+    # -W does not exist for icc in CFLAGS.
+    CFLAGS=`echo "$CFLAGS" | sed 's/-W[[[:space:]]]//g;s/-W$//'`
+
+    disabled_warnings=''
+    for warning in _INTEL_IGNORE_WARNINGS; do
+      disabled_warnings="$disabled_warnings,$warning"
+    done
+
+    # Remove the extra "," and extra whitespaces.
+    disabled_warnings=`echo "$disabled_warnings" | sed "s/^,//;s/[[[:space:]]]//g"`
+
+    INTEL_CFLAGS="-w1 -Werror -wd${disabled_warnings}"
+
+    CFLAGS="$CFLAGS $INTEL_CFLAGS"
+    CXXFLAGS="$CFLAGS $INTEL_CFLAGS"
+
+    [ac_cv_intel_cflags="$INTEL_CFLAGS"]
+  else
+    [ac_cv_intel_cflags="no extra flags"]
+  fi])
+  AC_SUBST([INTEL_CFLAGS])
+]) # buddy_INTEL