util/nvmutil: don't declare libc prototypes

i no longer use -Werror

these can actually conflict on some weird
systems, so better just remove them

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/nvmutil.c

@@ -704,17 +704,6 @@ static ino_t gbe_ino;
 static dev_t tmp_dev;
 static ino_t tmp_ino;
 
-/*
- * No need to declare feature
- * macros. I jus declare the
- * prototypes. Should be safe
- * on most Unices and compilers
- */
-char *mktemp(char *template);
-int fchmod(int fd, mode_t mode);
-void sync(void);
-int syncfs(int fd);
-
 static int tmp_fd = -1;
 static char *tname = NULL;
 
@@ -722,8 +711,6 @@ static char *tname = NULL;
 #define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
 #endif
 
-extern void *malloc();
-
 int
 main(int argc, char *argv[])
 {