execve.2: execve also returns E2BIG if a string is too long

The execve syscall returns -E2BIG in 3 cases:
- The total length of the command line arguments and environment is too large.
- An argument or environment string is longer than MAX_ARG_STRLEN.
- The full path to the executable exceeds MAX_ARG_STRLEN.

Spell out all 3 cases in the -E2BIG section.

Signed-off-by: Rik van Riel <riel@surriel.com>
Suggested-by: Matthew House <mattlloydhouse@gmail.com>

Author: rikvanriel

man2/execve.2

@@ -449,7 +449,8 @@ The total number of bytes in the environment
 .RI ( envp )
 and argument list
 .RI ( argv )
-is too large.
+is too large, an argument or environment string is too long, or
+the full path name to the executable is too long.
 .TP
 .B EACCES
 Search permission is denied on a component of the path prefix of