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/logd_writer.cpp b/liblog/logd_writer.cpp
index 4731487..ed906b3 100644
--- a/liblog/logd_writer.cpp
+++ b/liblog/logd_writer.cpp
@@ -38,6 +38,7 @@
 #include "config_write.h"
 #include "log_portability.h"
 #include "logger.h"
+#include "uio.h"
 
 /* branchless on many architectures. */
 #define min(x, y) ((y) ^ (((x) ^ (y)) & -((x) < (y))))