Build Script Refinements/Static Linking

[murl-digital]

This simplifies the build script a bit and adds a static linking feature flag for those who may want it

[revmischa]

Thanks for this, I added automatic static linking for windows and emscripten platforms in #13. Now there's some conflicts in the build script though, sorry. Want me to try to resolve them?

[revmischa]

are these needed?
should we really overwrite linker args just for linux/x86?

[murl-digital]

I've found that these are necessary otherwise the linker complains. I think rustc only links libc, not libc++, and gomp which I guess is a projectm dependency of some sort.

[murl-digital]

Thanks for this, I added automatic static linking for windows and emscripten platforms in #13. Now there's some conflicts in the build script though, sorry. Want me to try to resolve them?

Sorry for the belated response, I just now got a chance to check my github notifications. Sure, go ahead if you haven't already

[revmischa]

I've tried to merge your static build option with the latest, want to try it out? I hope that rustflags bit isn't necessary. It builds okay for me on macOS.

[murl-digital]

static linking doesn't work for me, ld vomits out a whole bunch of errors about extern functions not being found, here's a snippet:

          /home/draconium/.cargo/registry/src/index.crates.io-6f17d22bba15001f/projectm-sys-1.1.0-alpha.1/libprojectM/vendor/hlslparser/src/Engine.h:173:(.text._ZN2M45ArrayIPKcE11SetCapacityEi[_ZN2M45ArrayIPKcE11SetCapacityEi]+0x90): undefined reference to `__cxa_allocate_exception'
          /usr/bin/ld: /home/draconium/.cargo/registry/src/index.crates.io-6f17d22bba15001f/projectm-sys-1.1.0-alpha.1/libprojectM/vendor/hlslparser/src/Engine.h:173:(.text._ZN2M45ArrayIPKcE11SetCapacityEi[_ZN2M45ArrayIPKcE11SetCapacityEi]+0xa2): undefined reference to `std::bad_alloc::~bad_alloc()'
          /usr/bin/ld: /home/draconium/.cargo/registry/src/index.crates.io-6f17d22bba15001f/projectm-sys-1.1.0-alpha.1/libprojectM/vendor/hlslparser/src/Engine.h:173:(.text._ZN2M45ArrayIPKcE11SetCapacityEi[_ZN2M45ArrayIPKcE11SetCapacityEi]+0xac): undefined reference to `typeinfo for std::bad_alloc'
          /usr/bin/ld: /home/draconium/.cargo/registry/src/index.crates.io-6f17d22bba15001f/projectm-sys-1.1.0-alpha.1/libprojectM/vendor/hlslparser/src/Engine.h:173:(.text._ZN2M45ArrayIPKcE11SetCapacityEi[_ZN2M45ArrayIPKcE11SetCapacityEi]+0xb7): undefined reference to `__cxa_throw'
          collect2: error: ld returned 1 exit status

= note: some `extern` functions couldn't be found; some native libraries may need to be installed or have their path specified
  = note: use the `-l` flag to specify native libraries to link
  = note: use the `cargo:rustc-link-lib` directive to specify the native libraries to link with Cargo (see https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-link-lib)