Add a -fuse-init-array option to cc1 and map to the UseInitArray target
option. On the driver, check if we are using libraries from gcc 4.7 or newer
and if so pass -fuse-init-array to the frontend.
The crtbegin*.o files in gcc 4.7 no longer call the constructors listed in
.ctors, so we have to use .init_array.

llvm-svn: 158694
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index fcc260f..67429922 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1229,6 +1229,7 @@
   Opts.TrapFuncName = Args.getLastArgValue(OPT_ftrap_function_EQ);
   Opts.BoundsChecking = Args.getLastArgIntValue(OPT_fbounds_checking_EQ, 0,
                                                 Diags);
+  Opts.UseInitArray = Args.hasArg(OPT_fuse_init_array);
 
   Opts.FunctionSections = Args.hasArg(OPT_ffunction_sections);
   Opts.DataSections = Args.hasArg(OPT_fdata_sections);