CMake Build: Tidy up when -msse2 is passed to gcc (#622)

* Define CMAKE_ARM_COMPILER automatically (#469)

Makes use of CMAKE_SYSTEM_PROCESSOR to detect whether compilation is happening for an ARM architecture.

* Use the correct guard for specifying msse2 compiler flags.

Bruteforce and conversions were only checking against ANDROID which was not sufficient for ARM Linux builds.

* Remove redundant uses of the msse2 compiler flag.

* Globally set -msse2 for x86/amd64 gcc, Apple and Clang builds.

This is a change in behaviour. Prior to this commit, msse2 was only set for bruteforce and conversions.

msse and mfpmath=sse were already set globally prior to this change.

test_conformance/math_brute_force/CMakeLists.txt

@@ -21,26 +21,6 @@ set(${MODULE_NAME}_SOURCES
     unary_u.cpp
 )
 
-
-if (NOT ANDROID)
-set_source_files_properties(
-    FunctionList.cpp
-    Sleep.cpp
-    binary.cpp
-    binaryOperator.cpp
-    Utility.cpp
-    binary_i.cpp
-    binary_two_results_i.cpp
-    i_unary.cpp
-    macro_binary.cpp
-    macro_unary.cpp
-    mad.cpp
-    main.cpp     reference_math.cpp
-    ternary.cpp     unary.cpp     unary_two_results.cpp
-    unary_two_results_i.cpp unary_u.cpp
-    COMPILE_FLAGS -msse2    )
-endif(NOT ANDROID)
-
 if (NOT CMAKE_CL_64 AND NOT MSVC AND NOT ANDROID)
 set_source_files_properties(
 ${MODULE_NAME}_SOURCES