This should probably be in libcutils instead, so code that needs to
care about Windows can use readv/writev.
Change-Id: I7c2ceec3f742cee0e44f69fd4c88459376bd0e08
Move the liblog headers to log/ instead of cutils/ to complete
the separation of libcutils and liblog. cutils/log.h still
exists and includes log/log.h in order to support the many existing
modules that use cutils/log.h.
Change-Id: I2758c9f4aedcb809ca7ba8383d0f55041dd44345