build: link against shared BlocksRuntime

This allows libdispatch to build BlocksRuntime shared.

Author: compnerd

build.py

@@ -125,6 +125,7 @@
 		'-Xcc -fblocks'
 	])
 	foundation.LDFLAGS += '-ldispatch -L'+Configuration.current.variables["LIBDISPATCH_BUILD_DIR"]+'/src/.libs -rpath \$$ORIGIN '
+	foundation.LDFLAGS += '-L' + Configuration.current.variables['LIBDISPATCH_BUILD_DIR'] + ' -lBlocksRuntime '
 
 foundation.SWIFTCFLAGS = " ".join(swift_cflags)