Allow mkdir() race to succeed.

When two zygotes are starting, they both may try creating a mount
point after checking lstat().  The second mkdir() will result in
EEXIST, which is okay to ignore.

Bug: 7165469
Change-Id: If4411e2621f773c74cd05247899982fa5ebdd020
diff --git a/libcutils/fs.c b/libcutils/fs.c
index a9889b2..1226d44 100644
--- a/libcutils/fs.c
+++ b/libcutils/fs.c
@@ -55,8 +55,10 @@
 
 create:
     if (TEMP_FAILURE_RETRY(mkdir(path, mode)) == -1) {
-        ALOGE("Failed to mkdir(%s): %s", path, strerror(errno));
-        return -1;
+        if (errno != EEXIST) {
+            ALOGE("Failed to mkdir(%s): %s", path, strerror(errno));
+            return -1;
+        }
     }
 
 fixup: