build: Clean up recent expansion of Windows-related platforms

Author: rpavlik

src/CMakeLists.txt

@@ -26,18 +26,16 @@ include(GNUInstallDirs)
 
 ### Dependencies
 set(OpenGL_GL_PREFERENCE GLVND)
-if (NOT CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")
+if(NOT CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")
     # OpenGL package will be found for UWP apps but gl.h excludes UWP apps so it isn't actually usable.
-find_package(OpenGL)
+    find_package(OpenGL)
 endif()
 
 if(OPENGL_FOUND)
     add_definitions(-DXR_USE_GRAPHICS_API_OPENGL)
     message(STATUS "Enabling OpenGL support")
-elseif(BUILD_ALL_EXTENSIONS)
-    if (NOT CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")
-        message(FATAL_ERROR "OpenGL not found")
-    endif()
+elseif(BUILD_ALL_EXTENSIONS AND NOT CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")
+    message(FATAL_ERROR "OpenGL not found")
 endif()
 
 if(NOT CMAKE_VERSION VERSION_LESS 3.7.0)
@@ -91,9 +89,9 @@ elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
 endif()
 
 # /EHsc (support for C++ exceptions) is default in most configurations but seems missing when building arm/arm64.
-IF(MSVC)
-    SET(CMAKE_CXX_FLAGS "/EHsc")
-ENDIF(MSVC)
+if(MSVC)
+    set(CMAKE_CXX_FLAGS "/EHsc ${CMAKE_CXX_FLAGS}")
+endif()
 
 # This is a little helper library for setting up OpenGL
 if(OPENGL_FOUND AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/common/gfxwrapper_opengl.c")