Fix "undeclared identifier" error

This change is required to fix this error:

    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/stdio/printf_core/converter.cpp:9:
    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/stdio/printf_core/converter.h:12:
    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/stdio/printf_core/core_structs.h:13:
    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/__support/FPUtil/FPBits.h:17:
    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/__support/FPUtil/FloatProperties.h:12:
    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/__support/UInt128.h:12:
    In file included from /local/mnt/workspace/upstream/llvm-project/libc/src/__support/UInt.h:17:
    /local/mnt/workspace/upstream/llvm-project/libc/src/__support/integer_utils.h:51:13: error: use of undeclared identifier 'add_with_carry'
       51 |   auto r1 = add_with_carry(prod.lo, lo_hi.lo << 32, uint64_t(0));
          |             ^
    /local/mnt/workspace/upstream/llvm-project/libc/src/__support/integer_utils.h:55:13: error: use of undeclared identifier 'add_with_carry'
       55 |   auto r2 = add_with_carry(prod.lo, hi_lo.lo << 32, uint64_t(0));
          |             ^

Author: androm3da

libc/src/__support/integer_utils.h

@@ -13,6 +13,7 @@
 #include "src/__support/common.h"
 
 #include "bit.h"
+#include "math_extras.h"
 #include "number_pair.h"
 
 #include <stdint.h>