Fix CMAKE_BUILD_TYPE & bump datestamp.

Allow CMAKE_BUILD_TYPE to be set on the command line, and bump the
datestamp.

CMakeLists.txt

@@ -1,10 +1,13 @@
 cmake_minimum_required (VERSION 3.2)
-project (cpu_check VERSION 20180907 LANGUAGES C CXX)
+project (cpu_check VERSION 20181116 LANGUAGES C CXX)
 
 # Options
 # Use clang/llvm by default.
 # There's unexplained SEGVs with gcc 5.5.0 with -O2
 option(USE_CLANG "build with clang" ON)
+if (NOT CMAKE_BUILD_TYPE)
+	set(CMAKE_BUILD_TYPE Release)
+endif(NOT CMAKE_BUILD_TYPE)
 
 # Config header
 configure_file (
@@ -24,7 +27,6 @@ set(CMAKE_C_FLAGS_DEBUG "-g -Wall -O0")
 set(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -O0")
 set(CMAKE_C_FLAGS_RELEASE "-Wall -O2")
 set(CMAKE_CXX_FLAGS_RELEASE "-Wall -O2")
-set(CMAKE_BUILD_TYPE Release)
 
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)