Revert "expat-2.2.1 patch to allow compile on macOS and others"

This reverts commit 346121398b.

upstream fix is to fix configure to do a link check instead of
compile-only for getrandom.
See f78ed1ec52

Change-Id: Ia9a3f1c2091048778e2bf4773f9e31ae4700ce0c

external/expat/UnpackedTarball_expat.mk

@@ -14,7 +14,6 @@ $(eval $(call gb_UnpackedTarball_set_tarball,expat,$(EXPAT_TARBALL)))
 $(eval $(call gb_UnpackedTarball_add_patches,expat,\
 	external/expat/expat-winapi.patch \
 	external/expat/expat-iOS.patch \
-	external/expat/expat-2.2.1.patch \
 	external/expat/expat.getrandom_detection.patch.1 \
 ))
 

external/expat/expat-2.2.1.patch

@@ -1,21 +0,0 @@
---- misc/expat-2.1.0/lib/xmlparse.c	2017-06-22 15:44:06.000000000 +0200
-+++ misc/build/expat-2.1.0/lib/xmlparse.c	2017-06-22 15:50:36.000000000 +0200
-@@ -696,6 +696,8 @@
- 
- 
- #if defined(HAVE_GETRANDOM) || defined(HAVE_SYSCALL_GETRANDOM)
-+/* Patch buffer to undefined */
-+#undef buffer
- # include <errno.h>
- 
- # if defined(HAVE_GETRANDOM)
-@@ -704,6 +706,9 @@
- #  include <unistd.h>        /* syscall */
- #  include <sys/syscall.h>   /* SYS_getrandom */
- # endif
-+/* Set buffer back */
-+#define buffer (parser->m_buffer)
-+
- 
- /* Obtain entropy on Linux 3.17+ */
- static int