add a lib for rendering text in sdl2 and rules to make in makefile

SDL2_ttf/external/harfbuzz/TESTING.md

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+## Build and Test
+
+```shell
+meson build
+ninja -Cbuild
+meson test -Cbuild
+```
+
+### Debug with GDB
+
+```shell
+meson test -Cbuild --gdb testname
+```
+
+## Build and Run
+
+Depending on what area you are working in change or add `HB_DEBUG_<whatever>`.
+Values defined in `hb-debug.hh`.
+
+```shell
+CPPFLAGS='-DHB_DEBUG_SUBSET=100' meson setup build --reconfigure
+meson test -C build
+```
+
+### Run tests with asan
+
+```shell
+meson setup build -Db_sanitize=address --reconfigure
+meson compile -C build
+meson test -C build
+```
+
+### Enable Debug Logging
+
+```shell
+CPPFLAGS=-DHB_DEBUG_SUBSET=100 meson build --reconfigure
+ninja -C build
+```
+
+## Test with the Fuzzer
+
+FOr fuzzing, see `test/fuzzing/README.md`.
+
+## Profiling
+
+For profiling, see `perf/README.md`.
+