Raspberry Pi builds (#30)

Instructions, plus build option for running full-screen applications (without
X11) on vanilla 32-bit Raspbian installations.

This doesn't commit the actual .so binaries, since there are at least two
possible variants (as described in the README).

raylib/static/build_rpi_nox.py

@@ -0,0 +1,26 @@
+# Raspberry Pi native (non-X) build assumes the GPU libraries are installed in /opt/vc, as per Raspbian.
+# Raylib must be installed the compiled with:  cmake -DWITH_PIC=ON -DSHARED=ON -DSTATIC=ON -DPLATFORM='Raspberry Pi' ..
+
+from cffi import FFI
+import os
+import platform
+ffibuilder = FFI()
+
+
+ffibuilder.cdef(open("../raylib_modified.h").read().replace('RLAPI ', ''))
+
+
+ffibuilder.set_source("_raylib_cffi",
+                      """
+                           #include "../raylib.h"
+                      """,
+                      extra_link_args=['/usr/local/lib/libraylib.a',
+                                       '/opt/vc/lib/libEGL_static.a', '/opt/vc/lib/libGLESv2_static.a',
+                                       '-L/opt/vc/lib', '-lvcos', '-lbcm_host', '-lbrcmEGL', '-lbrcmGLESv2',
+                                       '-lm', '-lpthread', '-lrt'],
+                      )
+
+
+if __name__ == "__main__":
+    ffibuilder.compile(verbose=True)
+

raylib/static/build_rpi_nox_multi.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+if ! command -v pyenv &> /dev/null
+then
+    echo "Pyenv required: https://github.com/pyenv/pyenv-installer"
+    exit
+fi
+rm *arm-linux-gnueabihf.so
+pyenv install -s 3.9.1
+pyenv global 3.9.1
+pip3 install cffi
+python3 build_rpi_nox.py
+pyenv install -s 3.8.7
+pyenv global 3.8.7
+pip3 install cffi
+python3 build_rpi_nox.py
+pyenv install -s 3.7.9
+pyenv global 3.7.9
+pip3 install cffi
+python3 build_rpi_nox.py
+pyenv install -s 3.6.12
+pyenv global 3.6.12
+pip3 install cffi
+python3 build_rpi_nox.py