Remove unnecessary cmake quotes (#1625)

Author: a-maurice

cmake/external_rules.cmake

@@ -167,7 +167,7 @@ function(build_external_dependencies)
 # Propagate MacOS build flags.
  if(CMAKE_OSX_ARCHITECTURES)
  set(CMAKE_SUB_CONFIGURE_OPTIONS ${CMAKE_SUB_CONFIGURE_OPTIONS}
- -DCMAKE_OSX_ARCHITECTURES="${CMAKE_OSX_ARCHITECTURES}")
+ -DCMAKE_OSX_ARCHITECTURES=${CMAKE_OSX_ARCHITECTURES})
  endif()
  elseif(MSVC)
 # Propagate MSVC build flags.