By default, TDM-GCC-64 was using -march=x86-64, which for whatever reason caused issues when compiling with -O3. This makes scons force it to use -march=pentiumpro, the same as TDM-GCC-32. This also changes the release build to use -O3 instead of -O2, which matches the release build default used by cmake and code::blocks.
Added -march=pentiumpro on Windows for -O3 build
m5
Check if LTO is enabled
Add LTO flag
Added a flag to enable/disable LTO. Also pass optimization options to the linker, since older versions of gcc may not automatically use the same options for linking and compiling, and it seems likely clang doesn't do this either.
m3
These include an alternate mode of normalize_path() that enforces the
platform's preferred path delimiter (i.e. backslash on Windows) on the
output, and a function to detect whether a path refers to a root
directory.
Unfortunately, the last bit requires introducing a new link-time
dependency on Windows, against a system library. It's guaranteed to be
always there but it seems kind of a waste. The alternative would be to
hand-parse the string but that seems even more of a waste. And no,
Boost.Filesystem can't do this in a straightforward fashion right now.
Needed since 0180a72573a482683485821c8d43a82a546a86c6 introduces the
requirement of a C compiler in the building process. Otherwise we get
this from GCC 6.1.1:
cc1: error: command line option ‘-Wold-style-cast’ is valid for C++/ObjC++ but not for C [-Werror]
This adds -Wold-style-cast to the CCFLAGS when compiling everything
but lua. Lua requires an exception from the flags and there's thus a
workaround added.
This drops the required version to 2.0.2 on Linux and *BSD, as there are no known bugs that require us to have a later version on these platforms. Windows and Os X remains as 2.0.4.
How does doing otherwise even help reduce compile times unless you are
changing your build environment every time? It's just a liability that
makes it harder to do feature detection from other files. It's also
asymmetrical with regards to the CMake recipe.
