*: refactor handling of archived files. "tar f file.tar.lzma" now works too.

function                                             old     new   delta
unpack_Z_stream                                        -    1229   +1229
open_zipped                                            -     176    +176
unpack_bz2_stream_prime                                -      60     +60
tar_main                                             642     677     +35
find_main                                            406     418     +12
sv_main                                             1222    1233     +11
decode_format_string                                 829     837      +8
cmp_main                                             641     649      +8
popstring                                            134     140      +6
filter_accept_list_reassign                          120     125      +5
parse_and_put_prompt                                 800     804      +4
passwd_main                                         1053    1049      -4
make_new_name_gunzip                                 119     114      -5
rpm_main                                            1688    1670     -18
prepare                                              302     283     -19
xmalloc_open_zipped_read_close                       135      61     -74
uncompress                                          1229       -   -1229
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 8/5 up/down: 1554/-1349)        Total: 205 bytes

diff --git a/archival/bbunzip.c b/archival/bbunzip.c
index 65bb8b7..c796205 100644
--- a/archival/bbunzip.c
+++ b/archival/bbunzip.c
@@ -161,7 +161,7 @@
 static
 USE_DESKTOP(long long) int unpack_bunzip2(void)
 {
-	return unpack_bz2_stream(STDIN_FILENO, STDOUT_FILENO);
+	return unpack_bz2_stream_prime(STDIN_FILENO, STDOUT_FILENO);
 }
 
 int bunzip2_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -218,8 +218,8 @@
 
 	extension++;
 	if (strcmp(extension, "tgz" + 1) == 0
-#if ENABLE_FEATURE_GUNZIP_UNCOMPRESS
-	 || strcmp(extension, "Z") == 0
+#if ENABLE_FEATURE_SEAMLESS_Z
+	 || (extension[0] == 'Z' && extension[1] == '\0')
 #endif
 	) {
 		extension[-1] = '\0';
@@ -244,8 +244,8 @@
 		unsigned char magic2;
 
 		magic2 = xread_char(STDIN_FILENO);
-		if (ENABLE_FEATURE_GUNZIP_UNCOMPRESS && magic2 == 0x9d) {
-			status = uncompress(STDIN_FILENO, STDOUT_FILENO);
+		if (ENABLE_FEATURE_SEAMLESS_Z && magic2 == 0x9d) {
+			status = unpack_Z_stream(STDIN_FILENO, STDOUT_FILENO);
 		} else if (magic2 == 0x8b) {
 			status = unpack_gz_stream(STDIN_FILENO, STDOUT_FILENO);
 		} else {
@@ -351,7 +351,7 @@
 	if ((xread_char(STDIN_FILENO) != 0x1f) || (xread_char(STDIN_FILENO) != 0x9d)) {
 		bb_error_msg("invalid magic");
 	} else {
-		status = uncompress(STDIN_FILENO, STDOUT_FILENO);
+		status = unpack_Z_stream(STDIN_FILENO, STDOUT_FILENO);
 	}
 	return status;
 }