[ld, testsuite] Only run rdynamic-1 when "-rdynamic" option is supported by compiler

[Jiong Wang <jiong dot wang at foss dot arm dot com>]

This is the following error on arm bare-metal

  FAIL: Build rdynamic-1

"-rdynamic" is not supported by most bare-metal GCC, the only bare-metal I am
aware of is
 
  https://gcc.gnu.org/ml/gcc-patches/2011-02/msg00567.html

This patch implemented a -rdynamic availability check and gated "rdynamic-1"
build test.  GCC testsuite has added similar checks this week.

  https://gcc.gnu.org/ml/gcc-patches/2017-03/msg00258.html

No regression on X86-64/AArch64 native ld check.
OK for master?

Thanks.

ld/
2017-03-10  Jiong Wang  <jiong.wang@arm.com>

        * testsuite/lib/ld-lib.exp (check_rdynamic_available): New function.
        * testsuite/ld-elf/shared.exp (build_tests): Split tests which require
        GCC "-rdynamic" option support into "rdynamic_build_tests".
        (rdynamic_build_tests): New and only run it when
        check_rdynamic_available returns true.

diff --git a/ld/testsuite/ld-elf/shared.exp b/ld/testsuite/ld-elf/shared.exp
index 070915a791d6055e1ebc29262c8bccfbb7f9d764..dcbb52e0cdd4aa24c09ed2a5a21084f1bcca7eac 100644
--- a/ld/testsuite/ld-elf/shared.exp
+++ b/ld/testsuite/ld-elf/shared.exp
@@ -327,9 +327,6 @@ set build_tests {
   {"Build libpr2404b.a"
    "" ""
    {pr2404b.c} {} "libpr2404b.a"}
-  {"Build rdynamic-1"
-   "-rdynamic -Wl,--gc-sections" "-ffunction-sections"
-   {rdynamic-1.c} {{readelf {-s} rdynamic-1.rd}} "rdynamic-1"}
   {"Build dynamic-1"
    "-Wl,--dynamic-list,dynamic-1.syms -Wl,--gc-sections" "-ffunction-sections"
    {dynamic-1.c} {{readelf {-s} dynamic-1.rd}} "dynamic-1"}
@@ -370,6 +367,17 @@ set build_tests {
 
 run_cc_link_tests $build_tests
 
+set rdynamic_build_tests {
+  {"Build rdynamic-1"
+   "-rdynamic -Wl,--gc-sections" "-ffunction-sections"
+   {rdynamic-1.c} {{readelf {-s} rdynamic-1.rd}} "rdynamic-1"}
+}
+
+# Only build them when -rdynamic is supported by compiler.
+if [check_rdynamic_available] {
+  run_cc_link_tests $rdynamic_build_tests
+}
+
 set run_tests [list \
     [list "Run normal with libfoo.so" \
      "-Wl,--no-as-needed tmpdir/begin.o tmpdir/libfoo.so tmpdir/end.o" "" \
diff --git a/ld/testsuite/lib/ld-lib.exp b/ld/testsuite/lib/ld-lib.exp
index 42cfe1c824f7f40249baf694295f9f8e501e543a..7fb7efb2bc1297aca8228ee94aefd5dd2eec7bcc 100644
--- a/ld/testsuite/lib/ld-lib.exp
+++ b/ld/testsuite/lib/ld-lib.exp
@@ -2210,3 +2210,36 @@ proc check_libdl_available { } {
     }
     return $libdl_available_saved
 }
+
+# Return true if compiler driver support -rdynamic.
+
+proc check_rdynamic_available { } {
+    global rdynamic_available_saved
+    global CC
+
+    if {![info exists rdynamic_available_saved]} {
+        if { [which $CC] == 0 } {
+	    set rdynamic_available_saved 0
+	    return 0
+	}
+
+	set basename "tmpdir/rdynamic_avail_test[pid]"
+	set src ${basename}.c
+	set output ${basename}.out
+	set f [open $src "w"]
+	# Sample test file.
+	puts $f "int main (void)"
+	puts $f "{"
+	puts $f "  return 0; "
+	puts $f "}"
+	close $f
+	if [is_remote host] {
+	    set src [remote_download host $src]
+	}
+	set rdynamic_available_saved [run_host_cmd_yesno "$CC" "$src -o $output -rdynamic"]
+	remote_file host delete $src
+	remote_file host delete $output
+	file delete $src
+    }
+    return $rdynamic_available_saved
+}