libc: getdtablesize support

Issue #1847

repos/libports/src/lib/libc/dummies.cc

@@ -61,7 +61,6 @@ DUMMY(long  , -1, fpathconf, (int, int))
 DUMMY(int   , -1, freebsd7___semctl, (void))
 DUMMY(int   , -1, fstatat, (int, const char *, struct stat *, int))
 DUMMY(int   , -1, getcontext, (ucontext_t *))
-DUMMY(int   ,  0, getdtablesize, (void))
 DUMMY(gid_t ,  0, getegid, (void))
 DUMMY(uid_t ,  0, geteuid, (void))
 DUMMY(int   , -1, getfsstat, (struct statfs *, long, int))

repos/libports/src/lib/libc/fd_alloc.cc

@@ -81,3 +81,11 @@ File_descriptor *File_descriptor_allocator::find_by_libc_fd(int libc_fd)
 {
 	return metadata(reinterpret_cast<void*>(libc_fd));
 }
+
+
+/********************
+ ** Libc functions **
+ ********************/
+
+extern "C" int __attribute__((weak)) getdtablesize(void) {
+	PDBG("libc"); return MAX_NUM_FDS; }