[libc] fix another build failure from using limits.h (llvm#84827)

My GCC build is failing with issues similar why we added our own. Looks
like
we missed one spot. See also:

commit 72ce629 ("[libc] Add C23 limits.h header. (llvm#78887)")

Author: nickdesaulniers

libc/test/src/__support/CMakeLists.txt

@@ -78,6 +78,7 @@ add_libc_test(
   SRCS
     integer_to_string_test.cpp
   DEPENDS
+    libc.src.__support.CPP.limits
     libc.src.__support.CPP.string_view
     libc.src.__support.integer_literals
     libc.src.__support.integer_to_string

libc/test/src/__support/integer_to_string_test.cpp

@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "src/__support/CPP/limits.h"
 #include "src/__support/CPP/span.h"
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/UInt.h"
@@ -15,8 +16,6 @@
 
 #include "test/UnitTest/Test.h"
 
-#include "limits.h"
-
 using LIBC_NAMESPACE::IntegerToString;
 using LIBC_NAMESPACE::cpp::span;
 using LIBC_NAMESPACE::cpp::string_view;