title: how to use CMake file (GLOB SRCS *. ) with a build directory
body: <p>this is my current CMakeLists.txt file </p>
  
  <pre><code>cmake_minimum_required(VERSION 3.3)
  set(CMAKE_C_FLAGS " -Wall -g ")
  project( bmi )
  file( GLOB SRCS *.cpp *.h )
  add_executable( bmi ${SRCS}) 
  </code></pre>
  
  <p>This builds from my source directory, but I have to clean up all the extra files   after. My question is how do I build this from a build directory if all my source files are in the same source directory?     </p>
  
  <p>thanks </p>