ext/iconv/tests/bug52211.phpt: skip for non-GNU iconv implementations

This test ensures that iconv() will not return part of the string if
it encounters an error, but the particular error it wants to cause is
not portable. When the input sequence is not representable in the
output charset, POSIX says that "iconv() shall perform an
implementation-defined conversion on the character" rather than
fail. As far as I know, the only two implementations that go against
this recommendation (and return the error that this test is expecting)
are GNU libiconv and glibc.

This commit adds a SKIPIF check for the two GNU implementations to
ensure that an error is actually encountered during this test.

Author: orlitzky

ext/iconv/tests/bug52211.phpt

@@ -1,5 +1,16 @@
 --TEST--
 Bug #52211 (iconv() returns part of string on error)
+--SKIPIF--
+<?php
+// The two GNU iconvs (glibc and libiconv) fail if the input sequence
+// cannot be converted to the target charset, but most others
+// (including musl, FreeBSD, NetBSD, and Solaris) do not. POSIX says
+// that "iconv() shall perform an implementation-defined conversion on
+// the character," so this is likely to remain a GNUism.
+if (ICONV_IMPL != "libiconv" && ICONV_IMPL != "glibc") {
+    die("skip iconv impl may not fail on unconvertable sequences");
+}
+?>
 --EXTENSIONS--
 iconv
 --FILE--