[SM52 1/2] Upgrade Spidermonkey build system and binaries to 52.9.1

Of note is the change to static linking on *nix (MacOS already used it).
The logic is that we can only use one single version of SM, so that
advantage of dynamic linking is lost regardless. We might also see
performance gains in the future with LTO enabled. It is also slightly
easier to distribute the program as a result. Expect a negligible size
increase in the binary size (offset somewhat by no longer needing to
distribute .so files). Finally, it streamlines the build script.

Also noteworthy in this commit:
- The MacOS build script is folded back into the general build script.
- the perl/sed command is replaced by patching the configuration file,
which at least warns if it starts failing in the future.

Binaries for windows provided by @Itms
The bulk of the patching was also done by @Itms.

Tested by: Stan, Freagarach
Refs #4893

Differential Revision: https://code.wildfiregames.com/D3094
This was SVN commit r24202.

source/scriptinterface/ScriptTypes.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2016 Wildfire Games.
+/* Copyright (C) 2020 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -71,7 +71,7 @@
 # pragma GCC diagnostic pop
 #endif
 
-#if MOZJS_MAJOR_VERSION != 45
+#if MOZJS_MAJOR_VERSION != 52
 #error Your compiler is trying to use an incorrect major version of the \
 SpiderMonkey library. The only version that works is the one in the \
 libraries/spidermonkey/ directory, and it will not work with a typical \
@@ -79,7 +79,7 @@ system-installed version. Make sure you have got all the right files and \
 include paths.
 #endif
 
-#if MOZJS_MINOR_VERSION != 0
+#if MOZJS_MINOR_VERSION != 9
 #error Your compiler is trying to use an untested minor version of the \
 SpiderMonkey library. If you are a package maintainer, please make sure \
 to check very carefully that this version does not change the behaviour \