config: Fix host -rdynamic detection for build != host != target

The GCC_ENABLE_PLUGINS configure logic for detecting whether -rdynamic
is necessary and supported uses an appropriate objdump for $host
binaries (running on $build) in cases where $host is $build or
$target.

However, it is missing such logic in the case where $host is neither
$build nor $target, resulting in the compilers not being linked with
-rdynamic and plugins not being usable with such a compiler.  In fact
$ac_cv_prog_OBJDUMP, as used when $build = $host, is always an objdump
for $host binaries that runs on $build; that is, it's appropriate to
use in this case as well.

Tested in such a configuration that it does result in cc1 being linked
with -rdynamic as expected.  Also bootstrapped with no regressions for
x86_64-pc-linux-gnu.

config/
	* gcc-plugin.m4 (GCC_ENABLE_PLUGINS): Use
	export_sym_check="$ac_cv_prog_OBJDUMP -T" also when host is not
	build or target.

gcc/
	* configure: Regenerate.

libcc1/
	* configure: Regenerate.

1 files changed, 1 insertions, 1 deletions

diff --git a/libcc1/configure b/libcc1/configure
index 1a63a0e..2a914a0 100755
--- a/libcc1/configure
+++ b/libcc1/configure
@@ -15120,7 +15120,7 @@ fi
        elif test x$host = x$target; then
 	 export_sym_check="$gcc_cv_objdump -T"
        else
-	 export_sym_check=
+	 export_sym_check="$ac_cv_prog_OBJDUMP -T"
        fi
      ;;
    esac