* Make Android build optional on Nix
I want to build Servo without also installing the entire Android SDK.
This makes it so Android support is only built if `buildAndroid` is
true.
Signed-off-by: syvb <me@iter.ca>
* Add Android support to nix-shell if SERVO_ANDROID_BUILD set
---------
Signed-off-by: syvb <me@iter.ca>
* remove NixOS check from mach wrapper
* pin nixpkgs to fix jemalloc-sys + mozangle build scripts
* add stdenv.cc.cc to LD_LIBRARY_PATH to fix webrender build.rs
* add all buildInputs to LD_LIBRARY_PATH to fix ldd servo
* add glib + zlib to buildInputs to fix ldd servo
* working! patchelf --remove-rpath --set-interpreter
* undo changes that were ultimately unhelpful
* make compiled programs independent of Nix
* avoid installing patchelf’d toolchains in ~/.rustup
* remove another spurious change
* fix rustup pollution
* only enable on other distros when MACH_USE_NIX is set
In addition to minor changes for Windows, this forces Windows Python to
be used for all Windows builds (instead of using Windows Python only for
pc-windows-msvc builds).
We already redirect stdout, but the problem is that (at least on Windows/MSYS2), the `which` command tends to output things to stderr when failing:
```
$ ./mach build -d
which: no python2.7 in (/usr/local/bin:/usr/bin:/bin:/opt/bin:/c/Windows/System32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0/:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/c/Program Files/Java/jdk1.8.0_66/bin:/c/Python27:/c/Python27/Scripts)
```
This PR silences this noise.
