u-boot: fix binman/libfdt/pylibfdt build issue

Binman host tool in u-boot depends on libfdt library and pylibfdt module.
All the needed libraries and python modules are a part of u-boot.
This patch adds libfdt and pylibfdt to u-boot build:
- add required dependencies swig-native and python3-native
- fix python setup-tools issue: pass proper shared lib linker

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>

recipes-bsp/u-boot/files/u-boot-pylibfdt-native-build.patch

@@ -0,0 +1,12 @@
+diff --git a/tools/Makefile b/tools/Makefile
+index 5db2a54..54bd224 100644
+--- a/tools/Makefile
++++ b/tools/Makefile
+@@ -134,6 +134,7 @@ tools/_libfdt.so: $(LIBFDT_SRCS) $(LIBFDT_SWIG)
+ 	$(Q)unset CC; \
+ 	unset CROSS_COMPILE; \
+ 	LDFLAGS="$(HOSTLDFLAGS)" CFLAGS= VERSION="u-boot-$(UBOOTVERSION)" \
++		CC="$(HOSTCC)" LDSHARED="$(HOSTLDSHARED)" \
+ 		CPPFLAGS="$(_hostc_flags)" OBJDIR=tools \
+ 		SOURCES="$(LIBFDT_SRCS) tools/libfdt.i" \
+ 		SWIG_OPTS="-I$(srctree)/lib/libfdt -I$(srctree)/lib" \

recipes-bsp/u-boot/u-boot_2017.11.bb

@@ -2,7 +2,7 @@ DESCRIPTION="Upstream's U-boot configured for sunxi devices"
 
 require recipes-bsp/u-boot/u-boot.inc
 
-DEPENDS += "dtc-native"
+DEPENDS += " bc-native dtc-native swig-native python3-native "
 
 LICENSE = "GPLv2+"
 LIC_FILES_CHKSUM = "file://Licenses/README;md5=a2c678cfd4a4d97135585cad908541c6"
@@ -15,6 +15,7 @@ DEFAULT_PREFERENCE_sun7i="1"
 DEFAULT_PREFERENCE_sun8i="1"
 
 SRC_URI = "git://git.denx.de/u-boot.git;branch=master \
+           file://u-boot-pylibfdt-native-build.patch \
            file://boot.cmd \
            "
 
@@ -31,6 +32,8 @@ SPL_BINARY="u-boot-sunxi-with-spl.bin"
 UBOOT_ENV_SUFFIX = "scr"
 UBOOT_ENV = "boot"
 
+EXTRA_OEMAKE += ' HOSTLDSHARED="${BUILD_CC} -shared ${BUILD_LDFLAGS} ${BUILD_CFLAGS}" '
+
 do_compile_append() {
     ${B}/tools/mkimage -C none -A arm -T script -d ${WORKDIR}/boot.cmd ${WORKDIR}/${UBOOT_ENV_BINARY}
 }