[Patch] testsuite: Avoid TCL errors when ASAN/TSAN/UBSAN is not available

[Tobias Burnus]

In a --disable-libsanitizer build, I see errors such as:
  g++.sum:ERROR: can't read "asan_saved_library_path": no such variable

I believe the following patch is the right way to solve this.
OK?

Tobias

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testsuite: Avoid TCL errors when ASAN/TSAN/UBSAN is not available

gcc/testsuite/ChangeLog:

	* lib/asan-dg.ex (asan_finish): Only reset ld_library_path if
	saved-path variable exists.
	* lib/tsan-dg.exp (tsan_finish): Likewise.
	* lib/ubsan-dg.ex (ubsan_finish): Likewise.

diff --git a/gcc/testsuite/lib/asan-dg.exp b/gcc/testsuite/lib/asan-dg.exp
index 2124607245e..ce745dfdf8d 100644
--- a/gcc/testsuite/lib/asan-dg.exp
+++ b/gcc/testsuite/lib/asan-dg.exp
@@ -151,8 +151,10 @@ proc asan_finish { args } {
 	    unset TEST_ALWAYS_FLAGS
 	}
     }
-    set ld_library_path $asan_saved_library_path
-    set_ld_library_path_env_vars
+    if [info exists asan_saved_library_path ] {
+	set ld_library_path $asan_saved_library_path
+	set_ld_library_path_env_vars
+    }
     clear_effective_target_cache
 }
 
diff --git a/gcc/testsuite/lib/tsan-dg.exp b/gcc/testsuite/lib/tsan-dg.exp
index b5631a79bcf..6dcfd0a2f83 100644
--- a/gcc/testsuite/lib/tsan-dg.exp
+++ b/gcc/testsuite/lib/tsan-dg.exp
@@ -150,7 +150,9 @@ proc tsan_finish { args } {
     } else {
 	unset dg-do-what-default
     }
-    set ld_library_path $tsan_saved_library_path
-    set_ld_library_path_env_vars
+    if [info exists tsan_saved_library_path ] {
+	set ld_library_path $tsan_saved_library_path
+	set_ld_library_path_env_vars
+    }
     clear_effective_target_cache
 }
diff --git a/gcc/testsuite/lib/ubsan-dg.exp b/gcc/testsuite/lib/ubsan-dg.exp
index f4ab29e2add..31740e02ab4 100644
--- a/gcc/testsuite/lib/ubsan-dg.exp
+++ b/gcc/testsuite/lib/ubsan-dg.exp
@@ -141,7 +141,9 @@ proc ubsan_finish { args } {
 	    unset TEST_ALWAYS_FLAGS
 	}
     }
-    set ld_library_path $ubsan_saved_library_path
-    set_ld_library_path_env_vars
+    if [info exists ubsan_saved_library_path ] {
+	set ld_library_path $ubsan_saved_library_path
+	set_ld_library_path_env_vars
+    }
     clear_effective_target_cache
 }