Add conditional logic for including benchmarks.

CMakeLists.txt

@@ -44,7 +44,9 @@ option(SWIFT_BUILD_STATIC_STDLIB
     "Build static variants of the Swift standard library and SDK overlay"
     FALSE)
 
-
+option(SWIFT_INCLUDE_BENCHMARKS
+    "Create targets for running swift benchmarks"
+    TRUE)
 
 option(SWIFT_INCLUDE_TESTS "Create targets for building/running tests." TRUE)
 
@@ -600,6 +602,9 @@ if(SWIFT_BUILD_TOOLS)
 endif()
 add_subdirectory(utils)
 add_subdirectory(stdlib)
+if(SWIFT_INCLUDE_BENCHMARKS)
+  add_subdirectory(benchmark)
+endif()
 if(SWIFT_INCLUDE_TESTS)
   add_subdirectory(test)
   add_subdirectory(unittests)
@@ -647,5 +652,3 @@ execute_process(COMMAND date "+%Y%m%d"
 
 # CPack must be included *after* its configuration variables are set.
 include(CPack)
-
-add_subdirectory(benchmark)