Pass TZ=UTC to zip in rpmuncompress

The ZIP format has no notion of time zone, so timestamps are only
meaningful if it is known what time zone they were created in. Pass UTC
to prevent time stamps to depend on local time zone setting and make
builds from sources in zip files (more) reproducible.

Tested manually with Fedora's xz-java-1.9.zip as mentioned in the issue.

Resolves: rpm-software-management#2955

tools/rpmuncompress.c

@@ -44,7 +44,7 @@ struct archiveType_s {
     { COMPRESSED_NOT,	0,	"%{__cat}" ,	"",		"" },
     { COMPRESSED_OTHER,	0,	"%{__gzip}",	"-dc",		""  },
     { COMPRESSED_BZIP2,	0,	"%{__bzip2}",	"-dc",		"" },
-    { COMPRESSED_ZIP,	1,	"%{__unzip}",	"",		"-qq" },
+    { COMPRESSED_ZIP,	1,	"TZ=UTC %{__unzip}",	"",	"-qq" },
     { COMPRESSED_LZMA,	0,	"%{__xz}",	"-dc",		"" },
     { COMPRESSED_XZ,	0,	"%{__xz}",	"-dc",		"" },
     { COMPRESSED_LZIP,	0,	"%{__lzip}",	"-dc",		"" },