configure: Use AC_SYS_LARGEFILE

With musl-1.2.4 LFS support is being disabled and will later be entirely
removed where it is expected to use off_t and lseek rather than off64_t
and lseek64.

With glibc these types are also obsolete where it is expected to use the
_FILE_OFFSET_BITS define where off_t and lseek will become 64-bit
compatible versions when needed. This is set by AC_SYS_LARGEFILE.

configure.ac

@@ -13,6 +13,7 @@ AC_PROG_CXX
 AC_PROG_OBJC
 AC_STDC_HEADERS
 AC_PROG_INSTALL
+AC_SYS_LARGEFILE
 dnl AC_PROG_LIBTOOL
 AC_CONFIG_MACRO_DIR([m4])
 AC_C_BIGENDIAN

src/vfs_stdio.c

@@ -35,8 +35,6 @@
 #include <unistd.h>
 
 #ifndef __linux__
-#define off64_t off_t
-#define lseek64 lseek
 #define O_LARGEFILE 0
 #endif
 
@@ -169,7 +167,7 @@ stdio_seek (DB_FILE *stream, int64_t offset, int whence) {
         whence = SEEK_SET;
         offset = ((STDIO_FILE*)stream)->offs + offset;
     }
-    off64_t res = lseek64 (((STDIO_FILE *)stream)->stream, offset, whence);
+    off_t res = lseek (((STDIO_FILE *)stream)->stream, offset, whence);
     if (res == -1) {
         return -1;
     }
@@ -214,8 +212,8 @@ stdio_getlength (DB_FILE *stream) {
     return l;
 #else
     if (!f->have_size) {
-        int64_t size = lseek64 (f->stream, 0, SEEK_END);
-        lseek64 (f->stream, f->offs, SEEK_SET);
+        int64_t size = lseek (f->stream, 0, SEEK_END);
+        lseek (f->stream, f->offs, SEEK_SET);
 #ifdef USE_BUFFERING
         f->bufremaining = 0;
 #endif