add findclose() impl for comcom32 [#92]

This doesn't fix all the ff handle leaks.

32/Makefile

@@ -13,7 +13,7 @@ LINK_OPT =
 SRCS = $(SRCDIR)/command.c $(SRCDIR)/cmdbuf.c $(SRCDIR)/ms.c \
   $(SRCDIR)/env.c $(SRCDIR)/psp.c $(SRCDIR)/umb.c $(SRCDIR)/ae0x.c \
    $(SRCDIR)/compl.c \
-  $(SRCDIR)/version.c memmem.c fmemcpy.c
+  $(SRCDIR)/version.c memmem.c fmemcpy.c findclos.c
 ASSRCS = $(SRCDIR)/asm.S $(SRCDIR)/int23.S $(SRCDIR)/int0.S $(SRCDIR)/mouse.S
 OBJS = $(notdir $(SRCS:.c=.o)) $(notdir $(ASSRCS:.S=.o))
 CMD = comcom32.exe

32/findclos.c

@@ -0,0 +1,46 @@
+/*
+ *  dj64 - 64bit djgpp-compatible tool-chain
+ *  Copyright (C) 2021-2024  @stsp
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <dpmi.h>
+#include <libc/dosio.h>
+#include "findclos.h"
+
+int
+findclose(int handle)
+{
+  __dpmi_regs r;
+  int use_lfn = _USE_LFN;
+
+  if (use_lfn)
+  {
+    r.x.flags |= 1;  /* Always set CF before calling a 0x71NN function. */
+    r.x.bx = handle;
+    r.x.ax = 0x71a1;
+    __dpmi_int(0x21, &r);
+    if (!(r.x.flags & 1))
+      return 0;
+    errno = __doserr_to_errno(r.x.ax);
+    return errno;
+  }
+  return 0;
+}
+
+int __attribute__((alias("findclose")))
+__findclose(int handle);

32/findclos.h

@@ -0,0 +1,7 @@
+#ifndef FINDCLOS_H
+#define FINDCLOS_H
+
+#define HAVE_FINDCLOSE 1
+int findclose(int handle);
+
+#endif

src/command.h

@@ -361,6 +361,9 @@ static inline int file_copytime(int desc_handle, int src_handle)
 #include <unistd.h>
 #include <sys/exceptn.h>
 #include <dpmi.h>
+#ifndef DJ64
+#include "findclos.h"
+#endif
 
 #ifndef USE_CONIO_OUT
 #define cprintf printf