Fully initialize the struct in the Stat response

When providing a successful response to a Stat request, initialize
all the fields inside the struct.  This ensures everything is zeroed
out when it is later used.

(Use of uninitialized data was reported by valgrind)

src/HTTPFile.cc

@@ -145,6 +145,7 @@ ssize_t HTTPFile::Read(void *buffer, off_t offset, size_t size) {
 
 int HTTPFile::Fstat(struct stat *buff) {
 	if (m_stat) {
+		memset(buff, '\0', sizeof(struct stat));
 		buff->st_mode = 0600 | S_IFREG;
 		buff->st_nlink = 1;
 		buff->st_uid = 1;
@@ -232,6 +233,7 @@ int HTTPFile::Fstat(struct stat *buff) {
 	}
 
 	if (buff) {
+		memset(buff, '\0', sizeof(struct stat));
 		buff->st_mode = 0600 | S_IFREG;
 		buff->st_nlink = 1;
 		buff->st_uid = 1;

src/S3File.cc

@@ -172,6 +172,7 @@ int S3File::Fstat(struct stat *buff) {
 		current_newline = next_newline;
 	}
 
+	memset(buff, '\0', sizeof(struct stat));
 	buff->st_mode = 0600 | S_IFREG;
 	buff->st_nlink = 1;
 	buff->st_uid = 1;

src/S3FileSystem.cc

@@ -270,6 +270,7 @@ int S3FileSystem::Stat(const char *path, struct stat *buff, int opts,
 	}
 
 	if (object.empty()) {
+		memset(buff, '\0', sizeof(struct stat));
 		buff->st_mode = 0700 | S_IFDIR;
 		buff->st_nlink = 0;
 		buff->st_uid = 1;
@@ -291,6 +292,7 @@ int S3FileSystem::Stat(const char *path, struct stat *buff, int opts,
 		}
 	}
 	if (foundObj) {
+		memset(buff, '\0', sizeof(struct stat));
 		buff->st_mode = 0600 | S_IFREG;
 		buff->st_nlink = 1;
 		buff->st_uid = buff->st_gid = 1;
@@ -313,6 +315,7 @@ int S3FileSystem::Stat(const char *path, struct stat *buff, int opts,
 		return -ENOENT;
 	}
 
+	memset(buff, '\0', sizeof(struct stat));
 	buff->st_mode = 0700 | S_IFDIR;
 	buff->st_nlink = 0;
 	buff->st_uid = 1;