Linux i686 Build Support

This unblocks building on 32-bit Linux using the i686 triple.

Author: Kaiede

cmake/modules/SwiftSupport.cmake

@@ -101,6 +101,8 @@ function(get_swift_host_arch result_var_name)
     set("${result_var_name}" "itanium" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86")
     set("${result_var_name}" "i686" PARENT_SCOPE)
+  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "i686")
+    set("${result_var_name}" "i686" PARENT_SCOPE)
   else()
     message(FATAL_ERROR "Unrecognized architecture on host system: ${CMAKE_SYSTEM_PROCESSOR}")
   endif()