Driver: Support CC_PRINT_OPTIONS, used for logging the compile commands (in -v style) to a file.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99054 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/driver/driver.cpp b/tools/driver/driver.cpp
index 46f4124..2108c8f 100644
--- a/tools/driver/driver.cpp
+++ b/tools/driver/driver.cpp
@@ -218,6 +218,11 @@
 
   llvm::OwningPtr<Compilation> C;
 
+  // Handle CC_PRINT_OPTIONS and CC_PRINT_OPTIONS_FILE.
+  TheDriver.CCPrintOptions = !!::getenv("CC_PRINT_OPTIONS");
+  if (TheDriver.CCPrintOptions)
+    TheDriver.CCPrintOptionsFilename = ::getenv("CC_PRINT_OPTIONS_FILE");
+
   // Handle QA_OVERRIDE_GCC3_OPTIONS and CCC_ADD_ARGS, used for editing a
   // command line behind the scenes.
   std::set<std::string> SavedStrings;