[gn build] Set HAVE_MALLINFO2=1

[aeubanks]

Summary

I'm seeing deprecated warnings due to using mallinfo() instead of
mallinfo2().

../../llvm/lib/Support/Unix/Process.inc:98:10: warning: 'mallinfo' is deprecated [-Wdeprecated-declarations]

mi = ::mallinfo();

mallinfo2() is part of glibc 2.33 which was released in Feb 2021, which
is fairly recent but I think gn users should be using fairly up to date
glibcs.

If this breaks people we could make this a gn arg instead.

[thakis]

I wouldn't be terribly surprised if the linux bot on http://45.33.8.238/ doesn't have that yet, so please keep an eye out for it after landing this.

[thakis]

To everyone's (well, my) surprise, this broke the macOS bot instead: http://45.33.8.238/macm1/26108/step_4.txt

Should only set this to 1 on Linux and not on win and macOS :)

[aeubanks]

limit to Linux/Android

[peterwaller-arm]

Heads up, this did break my dev build and switching out libc is a nontrivial prospect for me for now. A configurable would be nice to have.

llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn

values = [
     "HAVE_FCNTL_H=1",
     "HAVE_FENV_H=1",
     "HAVE_FFI_CALL=",
     "HAVE_FFI_FFI_H=",
     "HAVE_FFI_H=",
     "HAVE_LIBPFM=",
     "HAVE_LIBPSAPI=",
     "HAVE_MALLCTL=",
-    "HAVE_MALLINFO2=",
     "HAVE_SIGNAL_H=1",
     "HAVE_STD_IS_TRIVIALLY_COPYABLE=1",
     "HAVE_STRERROR=1",
     "HAVE_SYS_STAT_H=1",
     "HAVE_SYS_TYPES_H=1",
     "HAVE_VALGRIND_VALGRIND_H=",
     "HAVE__ALLOCA=",
     "HAVE___ALLOCA=",
write_cmake_config("config") {
   ]
 
   if (current_os == "linux" || current_os == "android") {
     values += [
       "HAVE_FUTIMENS=1",
       "HAVE_LINK_H=1",
       "HAVE_LSEEK64=1",
       "HAVE_MALLINFO=1",
+      "HAVE_MALLINFO2=1",
       "HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC=1",
     ]
   } else {
     values += [
       "HAVE_FUTIMENS=",
       "HAVE_LINK_H=",
       "HAVE_LSEEK64=",
       "HAVE_MALLINFO=",
+      "HAVE_MALLINFO2=",
       "HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC=",
     ]
   }
 
   if (current_os == "mac") {
     values += [
       "HAVE_CRASHREPORTER_INFO=1",
       "HAVE_DECL_ARC4RANDOM=1",