Remove every uses of getGlobalContext() in LLVM (but the C API)

At the same time, fixes InstructionsTest::CastInst unittest: yes
you can leave the IR in an invalid state and exit when you don't
destroy the context (like the global one), no longer now.

This is the first part of http://reviews.llvm.org/D19094

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266379

llvm/tools/llvm-profdata/llvm-profdata.cpp

@@ -164,9 +164,9 @@ static void mergeSampleProfile(const WeightedFileVector &Inputs,
   auto Writer = std::move(WriterOrErr.get());
   StringMap<FunctionSamples> ProfileMap;
   SmallVector<std::unique_ptr<sampleprof::SampleProfileReader>, 5> Readers;
+  LLVMContext Context;
   for (const auto &Input : Inputs) {
-    auto ReaderOrErr =
-        SampleProfileReader::create(Input.Filename, getGlobalContext());
+    auto ReaderOrErr = SampleProfileReader::create(Input.Filename, Context);
     if (std::error_code EC = ReaderOrErr.getError())
       exitWithErrorCode(EC, Input.Filename);
 
@@ -365,7 +365,8 @@ static int showSampleProfile(std::string Filename, bool ShowCounts,
                              bool ShowAllFunctions, std::string ShowFunction,
                              raw_fd_ostream &OS) {
   using namespace sampleprof;
-  auto ReaderOrErr = SampleProfileReader::create(Filename, getGlobalContext());
+  LLVMContext Context;
+  auto ReaderOrErr = SampleProfileReader::create(Filename, Context);
   if (std::error_code EC = ReaderOrErr.getError())
     exitWithErrorCode(EC, Filename);