[test] Fix incorrect usage of swift_obj_root in unified builds

When doing an unified build (Swift being an external project of LLVM),
the Swift build is at `<llvm build dir>/tools/swift`, and that is the
value of `swift_obj_root`. However many products are actually placed in
`<llvm build dir>`, like `bin/`, `include/` and things like
`lib/swift/...` and others.

A couple of macros tests check the error messages printed by the
compiler against `swift_obj_root` (by the replacement done in
`PathSanitizingFileCheck` of `BUILD_DIR`) when it should have been
checking them against the top-level build directory, which will work in
both unified and non-unified builds (like `build-script` builds).

Author: drodriguez

test/lit.cfg

@@ -2978,12 +2978,12 @@ run_filecheck = '%s %s --allow-unused-prefixes --sanitize BUILD_DIR=%s --sanitiz
         shell_quote(sys.executable),
         shell_quote(config.PathSanitizingFileCheck),
         # LLVM Lit performs realpath with the config path, so all paths are relative
-        # to the real path. swift_obj_root and swift_src_root come from CMake, which
+        # to the real path. cmake_binary_dir and swift_src_root come from CMake, which
         # might not do real path. Because we have to match what Lit uses against what
         # we provide we use realpath here. Because PathSanitizingFileCheck only
         # understands sanitize patterns with forward slashes, and realpath normalizes
         # the slashes, we have to replace them back to forward slashes.
-        shell_quote(lit.util.abs_path_preserve_drive(swift_obj_root).replace("\\", "/")),
+        shell_quote(lit.util.abs_path_preserve_drive(cmake_binary_dir).replace("\\", "/")),
         shell_quote(lit.util.abs_path_preserve_drive(config.swift_src_root).replace("\\", "/")),
         shell_quote(config.filecheck),
         '--color' if config.color_output else '',

test/lit.site.cfg.in

@@ -16,6 +16,7 @@ import sys
 import lit.util
 
 config.cmake = "@CMAKE_COMMAND@"
+config.cmake_binary_dir = "@CMAKE_BINARY_DIR@"
 config.llvm_src_root = "@LLVM_MAIN_SRC_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"

validation-test/lit.site.cfg.in

@@ -14,6 +14,7 @@ import sys
 import platform
 
 config.cmake = "@CMAKE_COMMAND@"
+config.cmake_binary_dir = "@CMAKE_BINARY_DIR@"
 config.llvm_src_root = "@LLVM_MAIN_SRC_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"