Use gperf for the BuiltinFonts hash table

Instead of creating one by hand on runtime we create one at compile time

It's faster and lets us declare things as static const instead of just
static and also allows us to remove two init/destroy functions
6 jobs for use_gperf in 6 minutes and 30 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #1333822
build

00:02:45

passed #1333827
build_android

00:01:41

passed #1333823
build_clang_libcpp

00:06:30

passed #1333826
build_clazy

00:03:58

passed #1333825
build_mingw64_fedora

00:04:03

passed #1333824
build_ubuntu_16_04

00:01:36