Remove liblog/uio.c and <log/uio.h>

readv() isn't used by anyone, writev() has one easily replaced user.
uio.h can be left as a private header for windows compatibility with
struct iovec.

Test: build
Change-Id: I33d4c6bdee6fd818271f78ae06abdd2aa09430f2
diff --git a/liblog/pmsg_writer.cpp b/liblog/pmsg_writer.cpp
index c50c7f7..b2fc6d0 100644
--- a/liblog/pmsg_writer.cpp
+++ b/liblog/pmsg_writer.cpp
@@ -33,6 +33,7 @@
 #include "config_write.h"
 #include "log_portability.h"
 #include "logger.h"
+#include "uio.h"
 
 static int pmsgOpen();
 static void pmsgClose();