In simple-chrome, clang is a shell wrapper, it calls clang.elf, which is the
real binary, then, clang.elf calls clang.elf itself. It is the last invocation
"clang.elf -> clang.elf" that breaks, because direct calls to clang.elf misses
all environment setup in clang wrapper. Fix this by calling to clang wrapper
instead of clang.elf binary.

diff --git a/tools/clang/tools/driver/driver.cpp b/tools/clang/tools/driver/driver.cpp
index ea218d5..561f44f 100644
--- a/clang/tools/driver/driver.cpp
+++ b/clang/tools/driver/driver.cpp
@@ -409,6 +409,9 @@ int main(int argc_, const char **argv_) {
   }
 
   std::string Path = GetExecutablePath(argv[0], CanonicalPrefixes);
+  size_t PathLen = Path.length();
+  if (PathLen > 4 && Path.substr(PathLen - 4) == ".elf")
+    Path = Path.substr(0, PathLen - 4);
 
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts =
       CreateAndPopulateDiagOpts(argv);