[OpenMP] Enable executable lookup into driver directory.

[gtbercea]

Summary

Invoking the compiler inside a script causes the clang-offload-bundler executable to not be found. This patch enables the lookup for executables in the driver directory where the clang-offload-bundler resides.

[hfinkel]

I think this is fine, but please add a comment explaining that you're doing this to find (e.g., to find the offload bundler, etc.).

[gtbercea]

Add comment.

lib/Driver/ToolChains/Cuda.cpp

 
 CudaToolChain::CudaToolChain(const Driver &D, const llvm::Triple &Triple,
                              const ToolChain &HostTC, const ArgList &Args,
                              const Action::OffloadKind OK)
     : ToolChain(D, Triple, Args), HostTC(HostTC),
       CudaInstallation(D, HostTC.getTriple(), Args), OK(OK) {
   if (CudaInstallation.isValid())
     getProgramPaths().push_back(CudaInstallation.getBinPath());
+  // Lookup binaries into the driver directory, this is used to
+  // discover the clang-offload-bundler executable.
+  getProgramPaths().push_back(getDriver().Dir);
 }
 
 void CudaToolChain::addClangTargetOptions(
     const llvm::opt::ArgList &DriverArgs,
     llvm::opt::ArgStringList &CC1Args,
     Action::OffloadKind DeviceOffloadingKind) const {
   HostTC.addClangTargetOptions(DriverArgs, CC1Args, DeviceOffloadingKind);