LTO: Prune some warnings in the testsuite

Warnings like:

    warning: using serial compilation of 2 LTRANS jobs
    warning: visibility attribute not supported in this configuration; ignored\[^\n\]*" $text "" text

are pruned by lto.exp, but not for LTO testcases when run in other parts
of the testsuite. They will be, now.

gcc/testsuite/ChangeLog:

	PR testsuite/47334
	PR testsuite/103823
	* lib/prune.exp: Prune some warnings related to LTO and
	visibility.

gcc/testsuite/lib/prune.exp

@@ -96,6 +96,13 @@ proc prune_gcc_output { text } {
     # Ignore stabs obsoletion warnings
     regsub -all "(^|\n)\[^\n\]*\[Ww\]arning: STABS debugging information is obsolete and not supported anymore\[^\n\]*" $text "" text
 
+    # Ignore missing lto jobserver for tests that do more than 1 LTRANS unit
+    regsub -all "(^|\n)\[^\n\]*lto\[^\n\]*: warning: using serial compilation of \[^\n\]*" $text "" text
+    regsub -all "(^|\n)\[^\n\]*lto\[^\n\]*: note: see the \[^\n\]*'-flto' option documentation\[^\n\]* for more information" $text "" text
+
+    # Many tests that use visibility will still pass on platforms that don't support it.
+    regsub -all "(^|\n)\[^\n\]*lto1: warning: visibility attribute not supported in this configuration; ignored\[^\n\]*" $text "" text
+
     # If dg-enable-nn-line-numbers was provided, then obscure source-margin
     # line numbers by converting them to "NN" form.
     set text [maybe-handle-nn-line-numbers $text]