Fix typo in CMake error message "LLVM_LIBC_ENABLE_PROJECTS"->"LLVM_ENABLE_PROJECTS" (NFC)

GitOrigin-RevId: c32d695b099109118dbd50dd697fffe23cd9a529
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2e3ba5f..4995663 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -26,7 +26,7 @@
     add_custom_target(lint-libc)
   else()
     message(FATAL_ERROR "
-      'clang' and 'clang-tools-extra' are required in LLVM_LIBC_ENABLE_PROJECTS to
+      'clang' and 'clang-tools-extra' are required in LLVM_ENABLE_PROJECTS to
       lint llvm-libc. The linting step performs important checks to help prevent
       the introduction of subtle bugs, but it may increase build times.