Fix setting default cmake build type

Changes: Sets default cmake build type before
calling project(). Current version seems to follow
https://cmake.org/pipermail/cmake/2008-September/023808.html
however, it seems to miss the comment that:
"definition of CMAKE_BUILD_TYPE occurs in the PROJECT() command"
which means that setting cmake build type should happend prior
to calling PROJECT().

Fixes: lp:1785719
* https://bugs.launchpad.net/kicad/+bug/1785719

CMakeLists.txt

@@ -30,8 +30,6 @@ if(POLICY CMP0025)
   cmake_policy(SET CMP0025 NEW) # CMake 3.0
 endif()
 
-project( kicad )
-
 # Default to CMAKE_BUILD_TYPE = Release unless overridden on command line
 # http://www.cmake.org/pipermail/cmake/2008-September/023808.html
 if( DEFINED CMAKE_BUILD_TYPE )
@@ -40,6 +38,8 @@ else()
     set( CMAKE_BUILD_TYPE Release CACHE STRING "Set to either \"Release\" or \"Debug\"" )
 endif()
 
+project( kicad )
+
 include( GNUInstallDirs )
 
 # Path to local CMake modules.