Add '\' before -- to workaround dejagnu 1.4.4 which complains:
ERROR: bad switch "--no-define-common may not be used without -shared":...
* testsuite/ld-elf/pr21903c.d: Add '\' before --.
* testsuite/ld-elf/pr21903d.d: Likewise.
* testsuite/ld-elf/pr21903e.d: Likewise.
+2017-08-23 H.J. Lu <hongjiu.lu@intel.com>
+
+ * testsuite/ld-elf/pr21903c.d: Add '\' before --.
+ * testsuite/ld-elf/pr21903d.d: Likewise.
+ * testsuite/ld-elf/pr21903e.d: Likewise.
+
2017-08-23 H.J. Lu <hongjiu.lu@intel.com>
* testsuite/ld-x86-64/pie2.d: Updated.
#source: pr21903.s
#ld: --no-define-common
-#error: --no-define-common may not be used without -shared
+#error: \--no-define-common may not be used without -shared
#source: pr21903.s
#ld: --no-define-common -pie
#target: *-*-linux* *-*-gnu*
-#error: --no-define-common may not be used without -shared
+#error: \--no-define-common may not be used without -shared
#source: pr21903.s
#ld: -r --no-define-common
-#error: --no-define-common may not be used without -shared
+#error: \--no-define-common may not be used without -shared