[newlib-cygwin] Fix the documentation comment of checkint

[Jeff Johnston <jjohnstn@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=877a386d763f5068eafce6ef851002547b462edb

commit 877a386d763f5068eafce6ef851002547b462edb
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Tue Sep 18 14:14:53 2018 +0100

    Fix the documentation comment of checkint
    
    checkint in pow is not supposed to be used with 0, inf or nan inputs.

Diff:
---
 newlib/libm/common/pow.c    | 3 ++-
 newlib/libm/common/sf_pow.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/newlib/libm/common/pow.c b/newlib/libm/common/pow.c
index e02817e..c27d035 100644
--- a/newlib/libm/common/pow.c
+++ b/newlib/libm/common/pow.c
@@ -268,7 +268,8 @@ exp_inline (double x, double xtail, uint32_t sign_bias)
   return scale + scale * tmp;
 }
 
-/* Returns 0 if not int, 1 if odd int, 2 if even int.  */
+/* Returns 0 if not int, 1 if odd int, 2 if even int.  The argument is
+   the bit representation of a non-zero finite floating-point value.  */
 static inline int
 checkint (uint64_t iy)
 {
diff --git a/newlib/libm/common/sf_pow.c b/newlib/libm/common/sf_pow.c
index 2aa91c9..fcdab0e 100644
--- a/newlib/libm/common/sf_pow.c
+++ b/newlib/libm/common/sf_pow.c
@@ -127,7 +127,8 @@ exp2_inline (double_t xd, uint32_t sign_bias)
   return y;
 }
 
-/* Returns 0 if not int, 1 if odd int, 2 if even int.  */
+/* Returns 0 if not int, 1 if odd int, 2 if even int.  The argument is
+   the bit representation of a non-zero finite floating-point value.  */
 static inline int
 checkint (uint32_t iy)
 {