Fix build when swig is installed.

Patch out 'python' in a Makefile for ${MODPY_BIN} and add swig to
BUILD_DEPENDS so any related problems will be caught in future.

Problem reported by naddy and espie.

sysutils/u-boot/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.16 2017/03/03 03:27:28 jsg Exp $
+#	$OpenBSD: Makefile,v 1.17 2017/03/03 23:46:25 jsg Exp $
 
 BROKEN-sparc64=	Error: the specified option is not accepted in ISB at operand 1 -- isb sy
 
@@ -7,6 +7,7 @@ FLAVOR?=	arm
 
 COMMENT=	U-Boot firmware
 VERSION=	2017.03-rc3
+REVISION=	0
 DISTNAME=	u-boot-${VERSION}
 PKGNAME=	u-boot-${FLAVOR}-${VERSION}
 FULLPKGNAME=	${PKGNAME}
@@ -21,7 +22,8 @@ MASTER_SITES=	ftp://ftp.denx.de/pub/u-boot/
 EXTRACT_SUFX=	.tar.bz2
 PKG_ARCH=	*
 
-BUILD_DEPENDS=	devel/dtc
+BUILD_DEPENDS=	devel/dtc \
+		devel/swig
 MAKE_ENV=	KBUILD_VERBOSE=1
 
 MODULES=	lang/python
@@ -109,6 +111,9 @@ FILES=\
 	u-boot.imx \
 	u-boot-spl.kwb
 
+pre-build:
+	${SUBST_CMD} ${WRKBUILD}/tools/Makefile
+
 do-build:
 .for BOARD in ${BOARDS}
 	cd ${WRKSRC} && \

sysutils/u-boot/patches/patch-tools_Makefile

@@ -0,0 +1,12 @@
+$OpenBSD: patch-tools_Makefile,v 1.1 2017/03/03 23:46:25 jsg Exp $
+--- tools/Makefile.orig	Tue Feb 28 09:36:21 2017
++++ tools/Makefile	Sat Mar  4 10:28:42 2017
+@@ -120,7 +120,7 @@ _libfdt.so-sharedobjs += $(LIBFDT_OBJS)
+ libfdt:
+ 
+ tools/_libfdt.so: $(patsubst %.o,%.c,$(LIBFDT_OBJS)) tools/libfdt_wrap.c
+-	LDFLAGS="$(HOSTLDFLAGS)" python $(srctree)/lib/libfdt/setup.py \
++	LDFLAGS="$(HOSTLDFLAGS)" ${MODPY_BIN} $(srctree)/lib/libfdt/setup.py \
+ 		"$(_hostc_flags)" $^
+ 	mv _libfdt.so $@
+