removed unnessary bits that cmake should be doing for us; replace Misc::gcd with std::gcd

CMakeLists.txt

@@ -416,7 +416,7 @@ endif()
 
 
 if (CMAKE_CXX_COMPILER_ID STREQUAL GNU OR CMAKE_CXX_COMPILER_ID STREQUAL Clang)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wundef -Wno-unused-parameter -std=c++17 -pedantic -Wno-long-long")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wundef -Wno-unused-parameter -pedantic -Wno-long-long")
     add_definitions( -DBOOST_NO_CXX11_SCOPED_ENUMS=ON )
 
     if (APPLE)

apps/launcher/graphicspage.cpp

@@ -13,12 +13,13 @@
 
 #include <SDL_video.h>
 
+#include <numeric>
+
 #include <components/files/configurationmanager.hpp>
-#include <components/misc/gcd.hpp>
 
 QString getAspect(int x, int y)
 {
-    int gcd = Misc::gcd (x, y);
+    int gcd = std::gcd (x, y);
     int xaspect = x / gcd;
     int yaspect = y / gcd;
     // special case: 8 : 5 is usually referred to as 16:10

apps/openmw/mwgui/settingswindow.cpp

@@ -10,10 +10,10 @@
 #include <SDL_video.h>
 
 #include <iomanip>
+#include <numeric>
 
 #include <components/debug/debuglog.hpp>
 #include <components/misc/stringops.hpp>
-#include <components/misc/gcd.hpp>
 #include <components/misc/constants.hpp>
 #include <components/widgets/sharedstatebutton.hpp>
 #include <components/settings/settings.hpp>
@@ -60,7 +60,7 @@ namespace
 
     std::string getAspect (int x, int y)
     {
-        int gcd = Misc::gcd (x, y);
+        int gcd = std::gcd (x, y);
         int xaspect = x / gcd;
         int yaspect = y / gcd;
         // special case: 8 : 5 is usually referred to as 16:10

components/CMakeLists.txt

@@ -86,7 +86,7 @@ add_component_dir (esmterrain
     )
 
 add_component_dir (misc
-    gcd constants utf8stream stringops resourcehelpers rng messageformatparser weakcache
+    constants utf8stream stringops resourcehelpers rng messageformatparser weakcache
     )
 
 add_component_dir (debug

components/misc/gcd.hpp

@@ -1,13 +0,0 @@
-#ifndef MISC_GCD_H
-#define MISC_GCD_H
-
-namespace Misc
-{
-    // TODO: replace to the std::gcd() when the C++17 will be available.
-    int gcd(int a, int b)
-    {
-        return b == 0 ? a : gcd(b, a % b);
-    }
-}
-
-#endif