libcxx: Rename .hpp files in libcxx/test/support to .h

LLVM uses .h as its extension for header files.

Files renamed using:

    for f in libcxx/test/support/*.hpp; do git mv $f ${f%.hpp}.h; done

References to the files updated using:

    for f in $(git diff master | grep 'rename from' | cut -f 3 -d ' '); do
        a=$(basename $f);
        echo $a;
        rg -l $a libcxx | xargs sed -i '' "s/$a/${a%.hpp}.h/";
    done

HPP include guards updated manually using:

    for f in $(git diff master | grep 'rename from' | cut -f 3 -d ' '); do
      echo ${f%.hpp}.h ;
    done | xargs mvim

Differential Revision: https://reviews.llvm.org/D66104

llvm-svn: 369481
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: cc89063bff0f73ec7049a1dcb5d4688ae6806941
diff --git a/benchmarks/filesystem.bench.cpp b/benchmarks/filesystem.bench.cpp
index 3e49560..4c46444 100644
--- a/benchmarks/filesystem.bench.cpp
+++ b/benchmarks/filesystem.bench.cpp
@@ -1,7 +1,7 @@
 #include "benchmark/benchmark.h"
 #include "GenerateInput.hpp"
 #include "test_iterators.h"
-#include "filesystem_include.hpp"
+#include "filesystem_include.h"
 
 static const size_t TestNumInputs = 1024;