Avoid bgzf EOF check on modern MinGW releases.

Unfortunately this test is proving unreliable now following a change
to lseek so that it no longer returns -1 on pipes.

Fixes samtools/bcftools#1901

bgzf.c

@@ -1531,6 +1531,15 @@ int bgzf_mt_read_block(BGZF *fp, bgzf_job *j)
 
 static int bgzf_check_EOF_common(BGZF *fp)
 {
+#if defined(__MINGW32__) && HTS_GCC_AT_LEAST(12, 0)
+    // Modern MinGW appears to have started returning non-zero values from
+    // lseek when the file descriptor is a pipe.  It thinks SEEK_END is the
+    // size of the pipe buffer.  It doesn't set errno to ESPIPE either.
+
+    // See also test/test_bgzf.c test_check_EOF()
+    return 2;
+#endif
+
     uint8_t buf[28];
     off_t offset = htell(fp->fp);
     if (hseek(fp->fp, -28, SEEK_END) < 0) {

test/test_bgzf.c

@@ -621,16 +621,17 @@ static int test_index_load_dump(Files *f) {
 
 static int test_check_EOF(char *name, int expected) {
     BGZF *bgz = try_bgzf_open(name, "r", __func__);
-    int eof;
     if (!bgz) return -1;
-    eof = bgzf_check_EOF(bgz);
+#if !(defined(__MINGW32__) && HTS_GCC_AT_LEAST(12, 0))
+    int eof = bgzf_check_EOF(bgz);
     if (eof != expected) {
         fprintf(stderr, "%s : Unexpected result %d from bgzf_check_EOF on %s; "
                 "expected %d\n",
                 __func__, eof, name, expected);
         bgzf_close(bgz);
         return -1;
     }
+#endif
 
     return try_bgzf_close(&bgz, name, __func__, 0);
 }