[libc] Stop using LLVM's stdout in overlay mode tests

Summary:
This causes errors when running unit tests when it tries to use an
invalid stdio handle.

Fixes #98711

Author: jhuber6

libc/test/src/stdio/CMakeLists.txt

@@ -189,7 +189,6 @@ add_libc_test(
     printf_test.cpp
   DEPENDS
     libc.src.stdio.printf
-    libc.src.stdio.stdout
 )
 
 add_fp_unittest(
@@ -235,7 +234,6 @@ add_libc_test(
     vprintf_test.cpp
   DEPENDS
     libc.src.stdio.vprintf
-    libc.src.stdio.stdout
 )