Fix freetype build issue for javascript platform.
When disabling optimizations (SMID) in specific freetype, source files,
we need to make sure to copy all other CPPFLAGS, not just override them.
Include paths are processed from left to right, so we use Prepend to
ensure that paths to bundled thirdparty files will have precedence over
system paths (e.g. `/usr/include` should have lowest priority).
Many contributors (me included) did not fully understand what CCFLAGS,
CXXFLAGS and CPPFLAGS refer to exactly, and were thus not using them
in the way they are intended to be.
As per the SCons manual: https://www.scons.org/doc/HTML/scons-user/apa.html
- CCFLAGS: General options that are passed to the C and C++ compilers.
- CFLAGS: General options that are passed to the C compiler (C only;
not C++).
- CXXFLAGS: General options that are passed to the C++ compiler. By
default, this includes the value of $CCFLAGS, so that setting
$CCFLAGS affects both C and C++ compilation.
- CPPFLAGS: User-specified C preprocessor options. These will be
included in any command that uses the C preprocessor, including not
just compilation of C and C++ source files [...], but also [...]
Fortran [...] and [...] assembly language source file[s].
TL;DR: Compiler options go to CCFLAGS, unless they must be restricted
to either C (CFLAGS) or C++ (CXXFLAGS). Preprocessor defines go to
CPPFLAGS.
Also finally move freetype to its own env and disable warnings for it.
Still needs some work to fix the awkward situation of the freetype and
svg modules used in scene/ and editor/ respectively.
- The Windows, UWP, Android (on Windows) and Linux builds are
tested with Scons 3.0 alpha using Python 3.
- OSX and iOS should hopefully work but are not tested since
I don't have a Mac.
- Builds using SCons 2.5 and Python 2 should not be impacted.
All the warnings are factored out of the platform-specific files and moved to
SConstruct. Will have to check that it does not introduce regressions on some
platforms/compilers.
(cherry picked from commit 31107daa1a)
Before this change the libfreetype_builtin.a lib would be appended
at the very end of the linking flags, after system libs such as -lX11
or -lkernel32.
