pkg-autotools: don't disable dependency tracking if using <pkg>_OVERRIDE_SRCDIR

Include the --disable-dependency-tracking option in <pkg>_CONFIGURE_CMDS
only on the condition that <pkg>_OVERRIDE_SRCDIR is empty. Dependency
tracking is very welcome while developing in order to properly rebuild
when calling make <pkg>-rebuild for instance.

Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr>

package/pkg-autotools.mk

@@ -199,7 +199,7 @@ define $(2)_CONFIGURE_CMDS
 		--disable-documentation \
 		--with-xmlto=no \
 		--with-fop=no \
-		--disable-dependency-tracking \
+		$$(if $$($$(PKG)_OVERRIDE_SRCDIR),,--disable-dependency-tracking) \
 		--enable-ipv6 \
 		$$(DISABLE_NLS) \
 		$$(SHARED_STATIC_LIBS_OPTS) \
@@ -232,7 +232,7 @@ define $(2)_CONFIGURE_CMDS
 		--disable-debug \
 		--with-xmlto=no \
 		--with-fop=no \
-		--disable-dependency-tracking \
+		$$(if $$($$(PKG)_OVERRIDE_SRCDIR),,--disable-dependency-tracking) \
 		$$(QUIET) $$($$(PKG)_CONF_OPTS) \
 	)
 endef