libzip: Enable shared build.

src/libzip.mk

@@ -18,9 +18,7 @@ endef
 
 define $(PKG)_BUILD
     cd '$(1)' && ./configure \
-        --host='$(TARGET)' \
-        --prefix='$(PREFIX)/$(TARGET)' \
-        --disable-shared
+        $(MXE_CONFIGURE_OPTS)
     $(MAKE) -C '$(1)' -j '$(JOBS)' install $(MXE_DISABLE_CRUFT) SUBDIRS=lib
 
     '$(TARGET)-gcc' \
@@ -28,5 +26,3 @@ define $(PKG)_BUILD
         '$(2).c' -o '$(PREFIX)/$(TARGET)/bin/test-libzip.exe' \
         `'$(TARGET)-pkg-config' libzip --cflags --libs`
 endef
-
-$(PKG)_BUILD_SHARED =