Robert P. Day removed 8 gazillion occurrences of "extern" on function
definitions.  (That should only be on prototypes.)
diff --git a/libbb/printf.c b/libbb/printf.c
index 2cba317..e617232 100644
--- a/libbb/printf.c
+++ b/libbb/printf.c
@@ -145,7 +145,7 @@
 #endif
 
 #ifdef L_bb_vprintf
-extern int bb_vprintf(const char * __restrict format, va_list arg)
+int bb_vprintf(const char * __restrict format, va_list arg)
 {
 	return bb_vfprintf(stdout, format, arg);
 }
@@ -167,7 +167,7 @@
 #endif
 
 #ifdef L_bb_printf
-extern int bb_printf(const char * __restrict format, ...)
+int bb_printf(const char * __restrict format, ...)
 {
 	va_list arg;
 	int rv;