[MIPS] Allow errno safe logging

Change-Id: I35b4a9007572bec15ab7ba81aad3756fa96c5eb2
Signed-off-by: Chris Dearman <chris.dearman@imgtec.com>
Signed-off-by: Pete Delaney <piet.delaney@imgtec.com>

ndk/sources/android/libportable/common/include/log_portable.h

@@ -70,6 +70,17 @@ static inline char *portable_tag() {
 #define LOG_TAG PORTABLE_TAG
 #endif
 
+/*
+ * Override LOG_PRI() defined in ${AOSP}/system/core/include/cutils/log.h
+ * to preserve the value of errno while logging.
+ */
+#define LOG_PRI(priority, tag, ...) ({                      \
+    int _errno = errno;                                     \
+    int _rv = android_printLog(priority, tag, __VA_ARGS__); \
+    errno = _errno;                                         \
+    _rv;                   /* Returned to caller */         \
+})
+
 # include <cutils/log.h>
 
 # define PERROR(str)  {                                                                  \