[build] Rename clang-headers to clang-resource-headers

Summary:
The current install-clang-headers target installs clang's resource
directory headers. This is different from the install-llvm-headers
target, which installs LLVM's API headers. We want to introduce the
corresponding target to clang, and the natural name for that new target
would be install-clang-headers. Rename the existing target to
install-clang-resource-headers to free up the install-clang-headers name
for the new target, following the discussion on cfe-dev [1].

I didn't find any bots on zorg referencing install-clang-headers. I'll
send out another PSA to cfe-dev to accompany this rename.

[1] http://lists.llvm.org/pipermail/cfe-dev/2019-February/061365.html

Reviewers: beanz, phosek, tstellar, rnk, dim, serge-sans-paille

Subscribers: mgorny, javed.absar, jdoerfert, #sanitizers, openmp-commits, lldb-commits, cfe-commits, llvm-commits

Tags: #clang, #sanitizers, #lldb, #openmp, #llvm

Differential Revision: https://reviews.llvm.org/D58791

llvm-svn: 355340
diff --git a/clang/docs/LibTooling.rst b/clang/docs/LibTooling.rst
index 498baa2..2aaa508 100644
--- a/clang/docs/LibTooling.rst
+++ b/clang/docs/LibTooling.rst
@@ -187,8 +187,8 @@
 does.  Thus, the default location to look for builtin headers is in a path
 ``$(dirname /path/to/tool)/../lib/clang/3.3/include`` relative to the tool
 binary.  This works out-of-the-box for tools running from llvm's toplevel
-binary directory after building clang-headers, or if the tool is running from
-the binary directory of a clang install next to the clang binary.
+binary directory after building clang-resource-headers, or if the tool is
+running from the binary directory of a clang install next to the clang binary.
 
 Tips: if your tool fails to find ``stddef.h`` or similar headers, call the tool
 with ``-v`` and look at the search paths it looks through.