[lldb] add a warning if dirname is not in the PATH (llvm#164494)

This patch adds a check in lldb's API test CMakeLists file to ensure
that `dirname` is in the PATH, which is not obvious on Windows.

---------

Co-authored-by: nerix <[email protected]>

Author: charles-zablit

lldb/test/API/CMakeLists.txt

@@ -79,6 +79,16 @@ else()
   endif()
 endif()
 
+find_program(LLDB_DIRNAME_PATH dirname)
+if(LLDB_DIRNAME_PATH)
+  message(STATUS "Found dirname: ${LLDB_DIRNAME_PATH}")
+else()
+  message(STATUS "Could NOT find 'dirname'")
+  message(WARNING
+        "Many LLDB API tests require the GNU coreutils tools. Please make "
+        "sure they are installed and in PATH.")
+endif()
+
 if (TARGET clang)
   set(LLDB_DEFAULT_TEST_COMPILER "${LLVM_TOOLS_BINARY_DIR}/clang${CMAKE_EXECUTABLE_SUFFIX}")
 else()