libffi: do not build in a special directory

There's no need. It also breaks host builds.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/libffi/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=libffi
 PKG_VERSION:=3.2.1
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=ftp://sourceware.org/pub/libffi/
@@ -46,15 +46,6 @@ A layer must exist above libffi that handles type conversions for values passed
 between the two languages.
 endef
 
-CONFIGURE_PATH = build
-CONFIGURE_CMD = ../configure
-MAKE_PATH = build
-
-define Build/Configure
-	mkdir -p $(PKG_BUILD_DIR)/build
-	$(Build/Configure/Default)
-endef
-
 define Build/InstallDev
 	$(INSTALL_DIR) $(1)/usr/lib/pkgconfig
 	$(CP) \