Begin -print-on-crash output with semicolon (llvm#164903)

So it's treated as a comment and doesn't need to be manually removed
from the output when used as IR.

Author: InakiVA

llvm/lib/Passes/StandardInstrumentations.cpp

@@ -2499,7 +2499,7 @@ void PrintCrashIRInstrumentation::registerCallbacks(
       [&PIC, this](StringRef PassID, Any IR) {
         SavedIR.clear();
         raw_string_ostream OS(SavedIR);
-        OS << formatv("*** Dump of {0}IR Before Last Pass {1}",
+        OS << formatv("; *** Dump of {0}IR Before Last Pass {1}",
                       llvm::forcePrintModuleIR() ? "Module " : "", PassID);
         if (!isInteresting(IR, PassID, PIC.getPassNameForClassName(PassID))) {
           OS << " Filtered Out ***\n";

llvm/test/Other/print-on-crash.ll

@@ -17,7 +17,7 @@
 
 ; RUN: not --crash opt -print-on-crash -print-module-scope -passes=trigger-crash-module -filter-passes=blah < %s 2>&1 | FileCheck %s --check-prefix=CHECK_FILTERED
 
-; CHECK_SIMPLE: *** Dump of IR Before Last Pass {{.*}} Started ***
+; CHECK_SIMPLE: ; *** Dump of IR Before Last Pass {{.*}} Started ***
 ; CHECK_SIMPLE: @main
 ; CHECK_SIMPLE: entry:
 ; CHECK_NO_CRASH-NOT: *** Dump of IR