[libc++] Rename check-cxx-deps to cxx-test-depends for consistency

Several subprojects have targets that do the same thing, and they all
follow the same naming convention: llvm-test-depends, clang-test-depends,
lld-test-depends, etc.

This makes libc++ consistent with other LLVM projects.
Thanks to Duncan Exon Smith for noticing and suggesting the change.

Differential Revision: https://reviews.llvm.org/D94499

GitOrigin-RevId: 01a13f127a8b17c7827cc19302fc612532249795
diff --git a/docs/TestingLibcxx.rst b/docs/TestingLibcxx.rst
index 04930e1..ae01472 100644
--- a/docs/TestingLibcxx.rst
+++ b/docs/TestingLibcxx.rst
@@ -27,12 +27,12 @@
 After building libc++, you can run parts of the libc++ test suite by simply
 running ``llvm-lit`` on a specified test or directory. If you're unsure
 whether the required libraries have been built, you can use the
-`check-cxx-deps` target. For example:
+`cxx-test-depends` target. For example:
 
 .. code-block:: bash
 
   $ cd <monorepo-root>
-  $ make -C <build> check-cxx-deps # If you want to make sure the targets get rebuilt
+  $ make -C <build> cxx-test-depends # If you want to make sure the targets get rebuilt
   $ <build>/bin/llvm-lit -sv libcxx/test/std/re # Run all of the std::regex tests
   $ <build>/bin/llvm-lit -sv libcxx/test/std/depr/depr.c.headers/stdlib_h.pass.cpp # Run a single test
   $ <build>/bin/llvm-lit -sv libcxx/test/std/atomics libcxx/test/std/threads # Test std::thread and std::atomic
@@ -87,7 +87,7 @@
    .. code-block:: bash
 
      $ cmake <options> -DLIBCXX_TEST_CONFIG=<path-to-site-config>
-     $ make -C <build> check-cxx-deps
+     $ make -C <build> cxx-test-depends
      $ <build>/bin/llvm-lit -sv libcxx/test # will use your custom config file