[glib] gutils: Clarify return values of g_bit_nth_[lsf|msf]()

[Philip Withnall <pwithnall src gnome org>]

commit 91a6ec8d07eb521fc3f9be3bf7b7ae36a6108c88
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Tue Aug 25 10:49:06 2015 +0100

    gutils: Clarify return values of g_bit_nth_[lsf|msf]()
    
    Clarify in the documentation that both functions return -1 if no high
    bits could be found.

 glib/gutils.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/glib/gutils.c b/glib/gutils.c
index e229d0d..360a4d5 100644
--- a/glib/gutils.c
+++ b/glib/gutils.c
@@ -493,7 +493,8 @@ g_find_program_in_path (const gchar *program)
  * from 0 (least significant) to sizeof(#gulong) * 8 - 1 (31 or 63,
  * usually). To start searching from the 0th bit, set @nth_bit to -1.
  *
- * Returns: the index of the first bit set which is higher than @nth_bit
+ * Returns: the index of the first bit set which is higher than @nth_bit, or -1
+ *    if no higher bits are set
  */
 
 /**
@@ -507,7 +508,8 @@ g_find_program_in_path (const gchar *program)
  * usually). To start searching from the last bit, set @nth_bit to
  * -1 or GLIB_SIZEOF_LONG * 8.
  *
- * Returns: the index of the first bit set which is lower than @nth_bit
+ * Returns: the index of the first bit set which is lower than @nth_bit, or -1
+ *    if no lower bits are set
  */
 
 /**