ld: Fix testcase errors due to -shared not support.

Reviewed-by: Jim Wilson <jim.wilson.gcc@gmail.com>

ld/ChangeLog:

        * testsuite/ld-ctf/ctf.exp: Add shared lib check.
        * testsuite/ld-plugin/lto.exp: Add lto shared check.

ld/testsuite/ld-ctf/ctf.exp

@@ -28,6 +28,11 @@ if ![is_elf_format] {
     return 0
 }
 
+if ![check_shared_lib_support] {
+    unsupported "CTF needs shared lib support"
+    return 0
+}
+
 if {[info exists env(LC_ALL)]} {
     set old_lc_all $env(LC_ALL)
 }