CMake: move modules from CMakeTests/ -> CMake/

The name "CMakeTests" is inaccurate and irregular.

CMake/DolphinCompileDefinitions.cmake

@@ -0,0 +1,34 @@
+# Add a C or C++ compile definitions to the current scope
+#
+# dolphin_compile_definitions(def [def ...] [DEBUG_ONLY | RELEASE_ONLY])
+#
+# Can optionally add the definitions to Debug or Release configurations only, use this so we can
+# target multi-configuration generators like Visual Studio or Xcode.
+# Release configurations means NOT Debug, so it will work for RelWithDebInfo or MinSizeRel too.
+# The definitions are added to the COMPILE_DEFINITIONS folder property.
+# Supports generator expressions, unlike add_definitions()
+#
+# Examples:
+#   dolphin_compile_definitions(FOO) -> -DFOO
+#   dolphin_compile_definitions(_DEBUG DEBUG_ONLY) -> -D_DEBUG
+#   dolphin_compile_definitions(NDEBUG RELEASE_ONLY) -> -DNDEBUG
+#   dolphin_compile_definitions($<$<COMPILE_LANGUAGE:C>:THISISONLYFORC>)
+
+function(dolphin_compile_definitions)
+  set(defs ${ARGN})
+
+  list(GET defs -1 last_def)
+  list(REMOVE_AT defs -1)
+
+  set(genexp_config_test "1")
+  if(last_def STREQUAL "DEBUG_ONLY")
+    set(genexp_config_test "$<CONFIG:Debug>")
+  elseif(last_def STREQUAL "RELEASE_ONLY")
+    set(genexp_config_test "$<NOT:$<CONFIG:Debug>>")
+  else()
+    list(APPEND defs ${last_def})
+  endif()
+
+  set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS
+    "$<${genexp_config_test}:${ARGN}>")
+endfunction()