Remove Meson build system

Less maintenance overhead that way,
given that make/CMake now also do library versioning.

src/meson.build

@@ -1,22 +0,0 @@
-install_headers('raylib.h')
-
-source_c = [
-  'audio.c',
-  'core.c',
-  'models.c',
-  'rlgl.c',
-  'shapes.c',
-  'text.c',
-  'textures.c',
-  'utils.c',
-  'external/stb_vorbis.c',
-]
-
-# use 'meson --default-library=static builddir' to build as static, if no builddir yet exists
-# use 'mesonconf -Ddefault_library=static builddir' to change the type
-raylib = library('raylib',
-                  source_c,
-                  dependencies : [ glfw_dep, gl_dep, openal_dep, m_dep, x11_dep],
-                  install : true,
-                  version : '1.8.0')
-