[analyzer] Fix out-of-tree only clang build by not relaying on private header

[steakhal]

Summary

It turned out that the D78704 included a private LLVM header, which is excluded from the LLVM install target.
I'm substituting that #include with the public one by moving the necessary #define into that.
There was a discussion about this at D78704 and on the cfe-dev mailing list.

I'm also placing a note to remind others of this pitfall.

[mgorny]

Seems to work fine for me.

clang/unittests/StaticAnalyzer/FalsePositiveRefutationBRVisitorTest.cpp

 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
 #include "clang/StaticAnalyzer/Frontend/AnalysisConsumer.h"
 #include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
-#include "llvm/Config/config.h"
+#include "llvm/Config/llvm-config.h"
 #include "gtest/gtest.h"
 
 // FIXME: Use GTEST_SKIP() instead if GTest is updated to version 1.10.0
 #ifdef LLVM_WITH_Z3
 #define SKIP_WITHOUT_Z3
 #else
 #define SKIP_WITHOUT_Z3 return
 #endif

llvm/include/llvm/Config/config.h.cmake

 #ifndef CONFIG_H
 #define CONFIG_H
 
+// Include this header only under the llvm source tree.
+// This is a private header.
+
 /* Exported configuration */
 #include "llvm/Config/llvm-config.h"
 
 /* Bug report URL. */
 #define BUG_REPORT_URL "${BUG_REPORT_URL}"
 
 /* Define to 1 to enable backtraces, and to 0 otherwise. */
 #cmakedefine01 ENABLE_BACKTRACES

 #cmakedefine stricmp ${stricmp}
 
 /* Define to a function implementing strdup */
 #cmakedefine strdup ${strdup}
 
 /* Whether GlobalISel rule coverage is being collected */
 #cmakedefine01 LLVM_GISEL_COV_ENABLED
 
-/* Define if we have z3 and want to build it */
-#cmakedefine LLVM_WITH_Z3 ${LLVM_WITH_Z3}
-
 /* Define to the default GlobalISel coverage file prefix */
 #cmakedefine LLVM_GISEL_COV_PREFIX "${LLVM_GISEL_COV_PREFIX}"
 
 /* Whether Timers signpost passes in Xcode Instruments */
 #cmakedefine01 LLVM_SUPPORT_XCODE_SIGNPOSTS
 
 #endif

llvm/include/llvm/Config/llvm-config.h.cmake

 /* LLVM version string */
 #define LLVM_VERSION_STRING "${PACKAGE_VERSION}"
 
 /* Whether LLVM records statistics for use with GetStatistics(),
  * PrintStatistics() or PrintStatisticsJSON()
  */
 #cmakedefine01 LLVM_FORCE_ENABLE_STATS
 
+/* Define if we have z3 and want to build it */
+#cmakedefine LLVM_WITH_Z3 ${LLVM_WITH_Z3}
+
 /* Define if LLVM was built with a dependency to the libtensorflow dynamic library */
 #cmakedefine LLVM_HAVE_TF_API
 
 /* Define if LLVM was built with a dependency to the tensorflow compiler */
 #cmakedefine LLVM_HAVE_TF_AOT
 
 #endif