Driver: Sketch driver support for a CC_LOG_DIAGNOSTICS options, similar to the
existing CC_PRINT_OPTIONS and CC_PRINT_HEADERS, which can be used to
transparently capture the compiler diagnostics from a build.

llvm-svn: 129082
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 9d02dee..78720ed 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -63,11 +63,13 @@
     DefaultHostTriple(_DefaultHostTriple), DefaultImageName(_DefaultImageName),
     DriverTitle("clang \"gcc-compatible\" driver"),
     Host(0),
-    CCPrintOptionsFilename(0), CCPrintHeadersFilename(0), CCCIsCXX(false),
+    CCPrintOptionsFilename(0), CCPrintHeadersFilename(0),
+    CCLogDiagnosticsFilename(0), CCCIsCXX(false),
     CCCIsCPP(false),CCCEcho(false), CCCPrintBindings(false),
-    CCPrintOptions(false), CCPrintHeaders(false), CCCGenericGCCName("gcc"),
-    CheckInputsExist(true), CCCUseClang(true), CCCUseClangCXX(true),
-    CCCUseClangCPP(true), CCCUsePCH(true), SuppressMissingInputWarning(false) {
+    CCPrintOptions(false), CCPrintHeaders(false), CCLogDiagnostics(false),
+    CCCGenericGCCName("gcc"), CheckInputsExist(true), CCCUseClang(true),
+    CCCUseClangCXX(true), CCCUseClangCPP(true), CCCUsePCH(true),
+    SuppressMissingInputWarning(false) {
   if (IsProduction) {
     // In a "production" build, only use clang on architectures we expect to
     // work, and don't use clang C++.