Misc typos fixes in ./lib folder

Summary: Found via `codespell -q 3 -I ../clang-whitelist.txt -L uint,importd,crasher,gonna,cant,ue,ons,orign,ned`

Reviewers: teemperor

Reviewed By: teemperor

Subscribers: teemperor, jholewinski, jvesely, nhaehnle, whisperity, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D55475

llvm-svn: 348755
diff --git a/clang/lib/Driver/ToolChains/AMDGPU.cpp b/clang/lib/Driver/ToolChains/AMDGPU.cpp
index 451f31d..a421a09 100644
--- a/clang/lib/Driver/ToolChains/AMDGPU.cpp
+++ b/clang/lib/Driver/ToolChains/AMDGPU.cpp
@@ -104,7 +104,7 @@
     llvm::opt::ArgStringList &CC1Args,
     Action::OffloadKind DeviceOffloadingKind) const {
   // Default to "hidden" visibility, as object level linking will not be
-  // supported for the forseeable future.
+  // supported for the foreseeable future.
   if (!DriverArgs.hasArg(options::OPT_fvisibility_EQ,
                          options::OPT_fvisibility_ms_compat)) {
     CC1Args.push_back("-fvisibility");