gperftools: Build error when cross compiling for target-x86_64_musl

In building the latest commit from master, using the OpenWrt build system, I am getting this breakage error:

In file included from src/malloc_hook.cc:673:
src/malloc_hook_mmap_linux.h:63:39: error: 'off64_t' has not been declared
   63 |                               int fd, off64_t offset) __THROW {
      |                                       ^~~~~~~
src/malloc_hook_mmap_linux.h:152:24: error: 'off64_t' has not been declared
  152 |                int fd, off64_t offset  ) __THROW
      |                        ^~~~~~~
src/malloc_hook_mmap_linux.h:167:33: error: 'off64_t' has not been declared
  167 |                         int fd, off64_t offset) __THROW {
      |                                 ^~~~~~~

Complete build log. Link to Makefile used for building.