Mac fixes (#1795)

* macOS build fixes (#1773)

* macOS build fixes

Add missing headers
Threads_Pthreads: do not call pthread_setname_np() on macOS as it does not do
the same as on Linux
DebugStr() -> os_log()

* Make the project build with Makefiles on macOS

* Fix getting modifier key state on Mac (#1774)

We really need to clean up all Carbon calls here (many will go away when the
project switches to SDL2 for all platforms)

* Fix Xcode build; bump minimum version of macOS (#1775)

* Build fixes for the "Unix Makefiles" generator
Pass CMAKE_BUILD_TYPE to the external projects
* Fix indent

* Fix setting CFBundleExecutable value

* Improve handling of system libpng

Header mismatch can cause a crash, so force the non-system png.h
if WITH_SYSTEM_PNG=no

* Better handling of TRUE/FALSE with newer versions of jpeglib

* Add JPEG include directory

Xcode/Info.plist.in.xml

@@ -28,7 +28,7 @@
       </dict>
     </array>
     <key>CFBundleExecutable</key>
-    <string>PRODUCT_NAME</string>
+    <string>@SM_EXE_NAME@</string>
     <key>CFBundleGetInfoString</key>
     <string>@SM_EXE_NAME@ @SM_VERSION_TRADITIONAL@</string>
     <key>CFBundleIconFile</key>