Installer: Address review comments

Correctly set permissions on mac installer and create a missing folder

dist/installer/CMakeLists.txt

@@ -3,13 +3,14 @@ if(WIN32)
     set(PLATFORM "windows")
 elseif(APPLE)
     set(PLATFORM "mac")
-elseif(LINUX)
+elseif(UNIX)
     set(PLATFORM "linux")
 endif()
 
 set(BUILD_DIR "${CMAKE_BINARY_DIR}/installer")
 set(DIST_DIR "${BUILD_DIR}/dist")
 set(TARGET_FILE "${DIST_DIR}/citra-setup-${PLATFORM}")
+file(MAKE_DIRECTORY ${BUILD_DIR})
 
 # Adds a custom target that will run the BuildInstaller.cmake file
 # CMake can't just run a cmake function as a custom command, so this is a way around it.
@@ -19,4 +20,4 @@ add_custom_command(OUTPUT "${TARGET_FILE}"
     WORKING_DIRECTORY ${BUILD_DIR}
 )
 
-add_custom_target(installer DEPENDS ${TARGET_FILE})
+add_custom_target(installer DEPENDS ${TARGET_FILE})