Include translation unit filename in global ctor symbol names.

This makes it easier to see where a global ctor comes from, and it also makes
ASan's init order analyzer output easier to understand.  gcc does this too,
but only in -fPIC mode for some reason.  Don't do this for constructors with
explicit init priority.

Also prepend "sub_" before the 'I', that way regular constructors stay
lexicographically after symbols with init priority (because
ord('s') > ord('I')).  gold seems to ignore the name of constructor symbols,
and ld only looks at the symbol if it includes an init priority, which this
patch doesn't change.

Before: __GLOBAL_I_a
Now: __GLOBAL_sub_I_myfile.cc
llvm-svn: 208128
diff --git a/clang/test/CodeGenCXX/runtimecc.cpp b/clang/test/CodeGenCXX/runtimecc.cpp
index 646c61e..2044883 100644
--- a/clang/test/CodeGenCXX/runtimecc.cpp
+++ b/clang/test/CodeGenCXX/runtimecc.cpp
@@ -45,7 +45,7 @@
 
 // CHECK: declare arm_aapcscc void @__cxa_throw(i8*, i8*, i8*)
 
-// CHECK-LABEL: define internal arm_aapcscc void @_GLOBAL__I_a()
+// CHECK-LABEL: define internal arm_aapcscc void @_GLOBAL__sub_I_runtimecc.cpp()
 // CHECK:   call arm_aapcscc void @__cxx_global_var_init()