ld: Add "--" after regexp

Add "--" after regexp to support dejagnu 1.4.4.

	* testsuite/ld-elf/pr21903c.d: Remove '\' before --.
	* testsuite/ld-elf/pr21903d.d: Likewise.
	* testsuite/ld-elf/pr21903e.d: Likewise.
	* testsuite/lib/ld-lib.exp (run_dump_test): Add "--" after
	regexp.

ld/ChangeLog

@@ -1,3 +1,11 @@
+2017-08-24  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* testsuite/ld-elf/pr21903c.d: Remove '\' before --.
+	* testsuite/ld-elf/pr21903d.d: Likewise.
+	* testsuite/ld-elf/pr21903e.d: Likewise.
+	* testsuite/lib/ld-lib.exp (run_dump_test): Add "--" after
+	regexp.
+
 2017-08-24  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* testsuite/ld-i386/i386.exp (undefined_weak): Replace regexp

ld/testsuite/ld-elf/pr21903c.d

@@ -1,3 +1,3 @@
 #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

ld/testsuite/ld-elf/pr21903d.d

@@ -1,4 +1,4 @@
 #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

ld/testsuite/ld-elf/pr21903e.d

@@ -1,3 +1,3 @@
 #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

ld/testsuite/lib/ld-lib.exp

@@ -976,7 +976,7 @@ proc run_dump_test { name {extra_options {}} } {
                  && (($cmdret == 0) == ($check_ld(terminal) == 0)) \
                  && ((($check_ld(source) == "regex") \
                       && ($check_ld(regex) == "") == ($comp_output == "") \
-                      && [regexp $check_ld(regex) $comp_output]) \
+                      && [regexp -- $check_ld(regex) $comp_output]) \
                      || (($check_ld(source) == "file") \
                          && (![regexp_diff "tmpdir/ld.messages" "$srcdir/$subdir/$check_ld(file)"]))) } {
                 # We have the expected output from ld.