- AC_TRY_RUN does not work in case of cross-compilation environments.

Tests based on preprocessor CPP output, won't help either, as they
   don't spit out nice computed numerical values, but rather the
   #define itselve.

This commit was SVN r21364.

config/opal_check_compiler_version.m4

@@ -29,6 +29,7 @@ AC_DEFUN([OPAL_CHECK_COMPILER], [
     lower=m4_tolower($1)
     AC_CACHE_CHECK([for compiler $lower], opal_cv_compiler_[$1],
     [
+        if test "$cross_compiling" != "yes" ; then
             CPPFLAGS_orig=$CPPFLAGS
             CPPFLAGS="-I${top_ompi_srcdir}/ompi/include $CPPFLAGS"
             AC_TRY_RUN([
@@ -50,6 +51,9 @@ int main (int argc, char * argv[])
                 eval opal_cv_compiler_$1=0
             ])
             CPPFLAGS=$CPPFLAGS_orig
+        else
+            opal_cv_compiler_$1=0
+        fi
     ])
     AC_DEFINE_UNQUOTED([OPAL_BUILD_PLATFORM_COMPILER_$1], $opal_cv_compiler_[$1],
                        [The compiler $lower which OMPI was built with])
@@ -60,6 +64,7 @@ AC_DEFUN([OPAL_CHECK_COMPILER_STRINGIFY], [
     lower=m4_tolower($1)
     AC_CACHE_CHECK([for compiler $lower], opal_cv_compiler_[$1],
     [
+        if test "$cross_compiling" != "yes" ; then
             CPPFLAGS_orig=$CPPFLAGS
             CPPFLAGS="-I${top_ompi_srcdir}/ompi/include $CPPFLAGS"
             AC_TRY_RUN([
@@ -81,6 +86,9 @@ int main (int argc, char * argv[])
                 eval opal_cv_compiler_$1=UNKNOWN
             ])
             CPPFLAGS=$CPPFLAGS_orig
+        else
+            opal_cv_compiler_$1=UNKNOWN
+        fi
     ])
     AC_DEFINE_UNQUOTED([OPAL_BUILD_PLATFORM_COMPILER_$1], $opal_cv_compiler_[$1],
                        [The compiler $lower which OMPI was built with])