rev-list: make "estimate_bisect_steps" non static

Because it will be used from "bisect.c" too.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bisect.h

@@ -26,4 +26,6 @@ extern int show_bisect_vars(struct rev_list_info *info, int reaches, int all);
 
 extern int bisect_next_vars(const char *prefix);
 
+extern int estimate_bisect_steps(int all);
+
 #endif

builtin-rev-list.c

@@ -211,7 +211,7 @@ static inline int exp2i(int n)
  *
  * and P(2^n + x) < 0.5 means 2^n < 3x
  */
-static int estimate_bisect_steps(int all)
+int estimate_bisect_steps(int all)
 {
 	int n, x, e;