CMake: clean up dependencies
CMake: clean up dependencies

This change makes it so that source/Common and source/Main are only
referenced by the SwiftShader target. This will allow for better
target-based sub CMakeLists.

* Remove SharedLibrary.hpp/cpp from source list of libGLESv2 and
  libGLES_CM, as both of these depend on SwiftShader, which already
  builds these files.

* Make libEGL depend on SwiftShader, so we can remove
  SharedLibrary.hpp/cpp and Main/libX11.hpp/cpp from its
  source list.

Bug: b/145758253
Change-Id: If3d8e12cd09fb40d699080c2eeaa8243abe50512
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/43528
Tested-by: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>
Kokoro-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>

google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader