Do not bypass default CMake compiler checks on iOS.

- This should no longer be required on newer (3.5+) CMake versions and
  breaks the detection of supplementary compiler feature information
  such as the population of CMAKE_CXX_COMPILE_FEATURES which is required
  in order to compile Ceres.

Change-Id: Ibceab545925aa1e829320efa03fb74ef149cbb8b

cmake/iOS.cmake

diff --git a/cmake/iOS.cmake b/cmake/iOS.cmake
index 4221e9e..00752b4 100644
--- a/cmake/iOS.cmake
+++ b/cmake/iOS.cmake
@@ -224,12 +224,6 @@
 # Set the architectures for which to build.
 set(CMAKE_OSX_ARCHITECTURES ${IOS_ARCH} CACHE STRING "Build architecture for iOS")
 
-# Skip the platform compiler checks for cross compiling.
-set(CMAKE_CXX_COMPILER_FORCED TRUE)
-set(CMAKE_CXX_COMPILER_WORKS TRUE)
-set(CMAKE_C_COMPILER_FORCED TRUE)
-set(CMAKE_C_COMPILER_WORKS TRUE)
-
 # All iOS/Darwin specific settings - some may be redundant.
 set(CMAKE_SHARED_LIBRARY_PREFIX "lib")
 set(CMAKE_SHARED_LIBRARY_SUFFIX ".dylib")