Big cmake changes (#1514)

* Delete emscripten.cmake

This file is not needed at this point. EMSDK provides a toolchain file that has a lot more things in it and is better supported. Project currently works fine with the documentation provided in Emscripten SDK on how to build projects.

* First pass file separation.

The main two files are cleaner now. Only important things can be seen. Major changes include:
- raylib_static is now the alias instead of raylib
- Repeating segments are removed and pulled into separate files into <root>/cmake
- File is reordered to make more sense
- Installs are better structured
- Library is build into an output directory "raylib" instead of "src"
- All public header files are now set as a public header file
- Source files need to be listed (it is a bad practice to capture them using wildcards and file globs)
- CMakeLists are better commented

* Second pass on the example dirs.

They are quite complex so I'm more hesitant to do major changes. Also it works pretty well. Noticed that I forgot one of the seperated files and added it into src/CMakeLists.txt.

* Returned the header copy as it was convenient to have the public headers copied.

* A better description to the variable RAYLIB_IS_MAIN

Co-authored-by: Rob Loach <robloach@gmail.com>

* Remove debug message

Co-authored-by: Rob Loach <robloach@gmail.com>

* Improvements based on review.

* Simplify the install condition to not be platform specific as it was before.

Co-authored-by: Alexander Neumann <30894796+Neumann-A@users.noreply.github.com>

* Remove some CMAKE variables as they don't affect the build in any way

Co-authored-by: Alexander Neumann <30894796+Neumann-A@users.noreply.github.com>

Co-authored-by: Rob Loach <robloach@gmail.com>
Co-authored-by: Alexander Neumann <30894796+Neumann-A@users.noreply.github.com>

CMakeLists.txt

@@ -1,57 +1,27 @@
 cmake_minimum_required(VERSION 3.0)
+project(raylib)
+
+# Directory for easier includes
 set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 
+# RAYLIB_IS_MAIN determines whether the project is being used from root, or as a dependency.
 if ("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   set(RAYLIB_IS_MAIN TRUE)
 else()
   set(RAYLIB_IS_MAIN FALSE)
 endif()
 
-# Config options
-option(BUILD_EXAMPLES "Build the examples." ${RAYLIB_IS_MAIN})
-option(ENABLE_ASAN  "Enable AddressSanitizer (ASAN) for debugging (degrades performance)" OFF)
-option(ENABLE_UBSAN "Enable UndefinedBehaviorSanitizer (UBSan) for debugging" OFF)
-option(ENABLE_MSAN "Enable MemorySanitizer (MSan) for debugging (not recommended to run with ASAN)" OFF)
+# Sets compiler flags and language standard
+include(CompilerFlags)
 
-# This helps support the case where emsdk toolchain file is used
-# either by setting it with -DCMAKE_TOOLCHAIN_FILE=<path_to_emsdk>/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake
-# or by using "emcmake cmake -B build -S ." as described in https://emscripten.org/docs/compiling/Building-Projects.html
-if(EMSCRIPTEN)
-  SET(PLATFORM Web CACHE STRING "Forcing PLATFORM_WEB because EMSCRIPTEN was detected")
-endif()
+# Registers build options that are exposed to cmake
+include(CMakeOptions.txt)
 
-if(CMAKE_VERSION VERSION_LESS "3.1")
-  if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
-    set(CMAKE_C_FLAGS "-std=gnu99 ${CMAKE_C_FLAGS}")
-  endif()
-else()
-  set (CMAKE_C_STANDARD 99)
-endif()
+# Checks a few environment and compiler configurations
+include(BuildOptions)
 
-include(AddIfFlagCompiles)
-add_if_flag_compiles(-Werror=pointer-arith CMAKE_C_FLAGS)
-add_if_flag_compiles(-Werror=implicit-function-declaration CMAKE_C_FLAGS)
-# src/external/jar_xm.h does shady stuff
-add_if_flag_compiles(-fno-strict-aliasing CMAKE_C_FLAGS)
-
-if (ENABLE_ASAN)
-    add_if_flag_compiles(-fno-omit-frame-pointer CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
-    add_if_flag_compiles(-fsanitize=address CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
-endif()
-if (ENABLE_UBSAN)
-    add_if_flag_compiles(-fno-omit-frame-pointer CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
-    add_if_flag_compiles(-fsanitize=undefined CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
-endif()
-if (ENABLE_MSAN)
-    add_if_flag_compiles(-fno-omit-frame-pointer CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
-    add_if_flag_compiles(-fsanitize=memory CMAKE_C_FLAGS CMAKE_LINKER_FLAGS)
-endif()
-
-if (ENABLE_MSAN AND ENABLE_ASAN)
-    MESSAGE(WARNING "Compiling with both AddressSanitizer and MemorySanitizer is not recommended")
-endif()
-
-add_subdirectory(src)
+# Main sources directory (the second parameter sets the output directory name to raylib)
+add_subdirectory(src raylib)
 
 if (${BUILD_EXAMPLES})
   MESSAGE(STATUS "Building examples is enabled")