uboot-envtools: Add TARGET_LDFLAGS to fix PIE and RELRO

Forward the OpenWrt TARGET_LDFLAGS to the linker of the fw_printenv tool.
In addition also use the more standard make invocation script.
With this change the fw_printenv tool is built with PIE and Full RELRO
support when activated globally in OpenWrt.

Signed-off-by: Hauke Mehrtens <hauke.mehrtens@intel.com>
(cherry picked from commit b7b2be0b26)

package/boot/uboot-envtools/Makefile

@@ -51,16 +51,11 @@ define Build/Configure
 	touch $(PKG_BUILD_DIR)/include/generated/autoconf.h
 endef
 
-TARGET_CFLAGS += -I$(STAGING_DIR)/usr/include
+MAKE_FLAGS += \
-
-define Build/Compile
-	$(MAKE) -C $(PKG_BUILD_DIR) \
-		CROSS_COMPILE="$(TARGET_CROSS)" \
 	TARGET_CFLAGS="$(TARGET_CFLAGS)" \
-		HOSTLDFLAGS= \
+	TARGET_LDFLAGS="$(TARGET_LDFLAGS)" \
 	no-dot-config-targets=envtools \
 	envtools
-endef
 
 define Package/uboot-envtools/conffiles
 /etc/config/ubootenv

package/boot/uboot-envtools/patches/001-compile.patch

@@ -1,12 +1,15 @@
 --- a/tools/env/Makefile
 +++ b/tools/env/Makefile
-@@ -10,6 +10,10 @@
+@@ -10,6 +10,13 @@
  # with "CC" here for the maximum code reuse of scripts/Makefile.host.
  override HOSTCC = $(CC)
  
 +ifneq ($(TARGET_CFLAGS),)
 +HOSTCFLAGS = $(TARGET_CFLAGS)
 +endif
++ifneq ($(TARGET_LDFLAGS),)
++HOSTLDFLAGS = $(TARGET_LDFLAGS)
++endif
 +
  # Compile for a hosted environment on the target
  HOST_EXTRACFLAGS  = $(patsubst -I%,-idirafter%, $(filter -I%, $(UBOOTINCLUDE))) \