[analyzer] Remove redundant "returned to caller" suffix for compound literal in StackAddressEscape

This patch simplifies the diagnostic message in the core.StackAddrEscape
for stack memory associated with compound literals by removing the
redundant "returned to caller" suffix.
Example: https://godbolt.org/z/KxM67vr7c

```c
// clang --analyze -Xanalyzer -analyzer-checker=core.StackAddressEscape
void* compound_literal() {
  return &(unsigned short){((unsigned short)0x22EF)};
}
```

warning: Address of stack memory associated with a compound literal
declared on line 2 **returned to caller returned to caller**
[core.StackAddressEscape]

Author: z1nke

clang/lib/StaticAnalyzer/Checkers/StackAddrEscapeChecker.cpp

@@ -78,7 +78,7 @@ SourceRange StackAddrEscapeChecker::genName(raw_ostream &os, const MemRegion *R,
     const CompoundLiteralExpr *CL = CR->getLiteralExpr();
     os << "stack memory associated with a compound literal "
           "declared on line "
-       << SM.getExpansionLineNumber(CL->getBeginLoc()) << " returned to caller";
+       << SM.getExpansionLineNumber(CL->getBeginLoc());
     range = CL->getSourceRange();
   } else if (const auto *AR = dyn_cast<AllocaRegion>(R)) {
     const Expr *ARE = AR->getExpr();

clang/test/Analysis/stack-addr-ps.c

@@ -20,17 +20,21 @@ int* f3(int x, int *y) {
 
 void* compound_literal(int x, int y) {
   if (x)
-    return &(unsigned short){((unsigned short)0x22EF)}; // expected-warning{{Address of stack memory}} expected-warning{{address of stack memory}}
+    return &(unsigned short){((unsigned short)0x22EF)};
+  // expected-warning-re@-1{{Address of stack memory associated with a compound literal declared on line {{[0-9]+}} returned to caller [core.StackAddressEscape]}}
+  // expected-warning@-2{{address of stack memory}}
 
   int* array[] = {};
   struct s { int z; double y; int w; };
 
   if (y)
-    return &((struct s){ 2, 0.4, 5 * 8 }); // expected-warning{{Address of stack memory}} expected-warning{{address of stack memory}}
-    
+    return &((struct s){ 2, 0.4, 5 * 8 });
+  // expected-warning-re@-1{{Address of stack memory associated with a compound literal declared on line {{[0-9]+}} returned to caller [core.StackAddressEscape]}}
+  // expected-warning@-2{{address of stack memory}}
 
   void* p = &((struct s){ 42, 0.4, x ? 42 : 0 });
-  return p; // expected-warning{{Address of stack memory}}
+  return p;
+  // expected-warning-re@-1{{Address of stack memory associated with a compound literal declared on line {{[0-9]+}} returned to caller [core.StackAddressEscape]}}
 }
 
 void* alloca_test(void) {