liblog: audit declare LIBLOG_ABI_PUBLIC

- replace <sys/cdefs.h> with local "log_cdefs.h" which
  fortifies and expands definitions, adding LIBLOG_ABI_PUBLIC,
  LIBLOG_HIDDEN, LIBLOG_ABI_PRIVATE and LIBLOG_WEAK.
- clearly tag each interface as LIBLOG_ABI_PUBLIC, LIBLOG_HIDDEN,
  LIBLOG_ABI_PRIVATE, LIBLOG_WEAK or static depending on scope
- Add -fvisibility=hidden to ensure nothing else leaks
- some code standard adjustments

Bug: 27566046
Change-Id: Ic14033c4e6d833d973beb035ddc1c6134fb35a3f
diff --git a/liblog/uio.c b/liblog/uio.c
index f77cc49..d0184dc 100644
--- a/liblog/uio.c
+++ b/liblog/uio.c
@@ -16,17 +16,20 @@
 
 #if defined(_WIN32)
 
-#include <log/uio.h>
 #include <unistd.h>
 
-int  readv( int  fd, struct iovec*  vecs, int  count )
+#include <log/uio.h>
+
+#include "log_cdefs.h"
+
+LIBLOG_ABI_PUBLIC int readv(int fd, struct iovec *vecs, int count)
 {
     int   total = 0;
 
     for ( ; count > 0; count--, vecs++ ) {
         char*  buf = vecs->iov_base;
         int    len = vecs->iov_len;
-        
+
         while (len > 0) {
             int  ret = read( fd, buf, len );
             if (ret < 0) {
@@ -46,14 +49,14 @@
     return total;
 }
 
-int  writev( int  fd, const struct iovec*  vecs, int  count )
+LIBLOG_ABI_PUBLIC int writev(int fd, const struct iovec *vecs, int count)
 {
     int   total = 0;
 
     for ( ; count > 0; count--, vecs++ ) {
         const char*  buf = vecs->iov_base;
         int          len = vecs->iov_len;
-        
+
         while (len > 0) {
             int  ret = write( fd, buf, len );
             if (ret < 0) {
@@ -69,7 +72,7 @@
             len   -= ret;
         }
     }
-Exit:    
+Exit:
     return total;
 }