Because of a Libiberty hack, getopt on GNU libc (2.25 or earlier) is
currently unusable on sim, causing a regression on CentOS 7.
This is caused as follows:
1. If HAVE_DECL_GETOPT is defined (getopt declaration with known prototype
is detected while configuration), a declaration of getopt in
"include/getopt.h" is suppressed.
The author started to define HAVE_DECL_GETOPT in sim with the commit
340aa4f687 ("sim: Check known getopt definition existence").
2. GNU libc (2.25 or earlier)'s <unistd.h> includes <getopt.h> with a
special purpose macro defined to declare only getopt function but due
to include path (not tested while configuration), it causes <unistd.h>
to include Libiberty's "include/getopt.h".
3. If both 1. and 2. are satisfied, despite that <unistd.h> tries to
declare getopt by including <getopt.h>, "include/getopt.h" does not do
so, causing getopt function undeclared.
Getting rid of "include/getopt.h" (e.g. renaming this header file) is the
best solution to avoid hacking but as a short-term solution, this commit
replaces getopt with getopt_long under sim/.
dd6c5a9217