[analyzer] Fix StdLibraryFunctionsChecker crash on macOS

Summary:
EOF macro token coming from a PCH file on macOS while marked as literal,
doesn't contain any literal data.  This causes crash on every project
using PCHs.

This commit doesn't resolve the problem with PCH (maybe it was
designed like this for a purpose) or with `tryExpandAsInteger`, but
rather simply shoots off a crash itself.

Differential Revision: https://reviews.llvm.org/D81916

clang/lib/StaticAnalyzer/Core/CheckerHelpers.cpp

@@ -128,7 +128,9 @@ llvm::Optional<int> tryExpandAsInteger(StringRef Macro,
 
   // Parse an integer at the end of the macro definition.
   const Token &T = FilteredTokens.back();
-  if (!T.isLiteral())
+  // FIXME: EOF macro token coming from a PCH file on macOS while marked as
+  //        literal, doesn't contain any literal data
+  if (!T.isLiteral() || !T.getLiteralData())
     return llvm::None;
   StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
   llvm::APInt IntValue;

clang/test/Analysis/pch_crash.cpp

@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.15.0 -emit-pch -o %t %s
+// RUN: %clang_analyze_cc1 -triple x86_64-apple-macosx10.15.0 -include-pch %t \
+// RUN:   -analyzer-checker=core,apiModeling -verify %s
+//
+// RUN: %clang_cc1 -emit-pch -o %t %s
+// RUN: %clang_analyze_cc1 -include-pch %t \
+// RUN:   -analyzer-checker=core,apiModeling -verify %s
+
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+// Pre-compiled header
+
+int foo();
+
+// Literal data for this macro value will be null
+#define EOF -1
+
+#else
+// Source file
+
+int test() {
+  // we need a function call here to initiate erroneous routine
+  return foo(); // no-crash
+}
+
+#endif