lib/string.c: use the name "C-string" in comments

For strncpy() and friends the source string may or may not have an actual
NUL character at the end.  The documentation is confusing in this because
it specifically mentions that you are passing a "NUL-terminated" string.
Wikipedia says that "C-string" is an alternative name we can use instead.

http://en.wikipedia.org/wiki/Null-terminated_stringSigned-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/string.c

@@ -107,7 +107,7 @@ EXPORT_SYMBOL(strcpy);
 
 #ifndef __HAVE_ARCH_STRNCPY
 /**
- * strncpy - Copy a length-limited, %NUL-terminated string
+ * strncpy - Copy a length-limited, C-string
  * @dest: Where to copy the string to
  * @src: Where to copy the string from
  * @count: The maximum number of bytes to copy
@@ -136,7 +136,7 @@ EXPORT_SYMBOL(strncpy);
 
 #ifndef __HAVE_ARCH_STRLCPY
 /**
- * strlcpy - Copy a %NUL terminated string into a sized buffer
+ * strlcpy - Copy a C-string into a sized buffer
  * @dest: Where to copy the string to
  * @src: Where to copy the string from
  * @size: size of destination buffer
@@ -182,7 +182,7 @@ EXPORT_SYMBOL(strcat);
 
 #ifndef __HAVE_ARCH_STRNCAT
 /**
- * strncat - Append a length-limited, %NUL-terminated string to another
+ * strncat - Append a length-limited, C-string to another
  * @dest: The string to be appended to
  * @src: The string to append to it
  * @count: The maximum numbers of bytes to copy
@@ -211,7 +211,7 @@ EXPORT_SYMBOL(strncat);
 
 #ifndef __HAVE_ARCH_STRLCAT
 /**
- * strlcat - Append a length-limited, %NUL-terminated string to another
+ * strlcat - Append a length-limited, C-string to another
  * @dest: The string to be appended to
  * @src: The string to append to it
  * @count: The size of the destination buffer.