[libc][Obvious] Add string tests to non-full-build mode.

GitOrigin-RevId: 7b5ab956b1ffa16feabc537e057148530156a1c3
diff --git a/test/src/CMakeLists.txt b/test/src/CMakeLists.txt
index 8638dea..1d7c470 100644
--- a/test/src/CMakeLists.txt
+++ b/test/src/CMakeLists.txt
@@ -2,6 +2,7 @@
 add_subdirectory(errno)
 add_subdirectory(fenv)
 add_subdirectory(math)
+add_subdirectory(string)
 
 if(NOT LLVM_LIBC_FULL_BUILD)
   return()
@@ -11,7 +12,6 @@
 add_subdirectory(signal)
 add_subdirectory(stdio)
 add_subdirectory(stdlib)
-add_subdirectory(string)
 add_subdirectory(sys)
 add_subdirectory(threads)
 add_subdirectory(time)