libcanfestival: fix several small build process issues

This patch tries to address the following package issues:

- the upstream hg repository seems to contain some invalid timestamps,
  at least the following warning are generated during package compilation
  (only one example):

  emcy.c: Timestamp out of range; substituting 2514-05-30 01:53:03.999999999

  This can be fixed by touching all files after unpacking, thus tar is
  now given the -m switch.

- one or more LEDE buildbot(s) do not have hg tool installed and thus are not
  able to checkout the sources from upstream

  This patch populates PKG_MIRROR_HASH in the hope that the buildbot's first
  try is to download an already packed source tarball prior to checkout it out
  from upstream.

- While at packaging from upstream, use the common infrastructure, i.e. use
  a source date etc. This also results in tar.xz files and thus reduces the
  disk footprint a little bit.

- during compilation the follwing warning could be observed:

  cc1: note: someone does not honour copts correctly, passed 0 times

  To silent down these warning, patch the Makefiles and pass the expected
  option.

Important note: changes are only compile tested due to missing hardware at
hand.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

libs/libcanfestival/patches/004-honour-copts.patch

@@ -0,0 +1,44 @@
+--- a/drivers/can_socket/Makefile.in
++++ b/drivers/can_socket/Makefile.in
+@@ -23,7 +23,7 @@
+ 
+ CC = SUB_CC
+ OPT_CFLAGS = -O2
+-CFLAGS = SUB_OPT_CFLAGS
++CFLAGS = SUB_OPT_CFLAGS -fhonour-copts
+ PROG_CFLAGS = SUB_PROG_CFLAGS
+ PREFIX = SUB_PREFIX
+ TARGET = SUB_TARGET
+--- a/src/Makefile.in
++++ b/src/Makefile.in
+@@ -101,7 +101,7 @@ uninstall:
+ 	rm -rf $(DESTDIR)$(PREFIX)/include/canfestival
+ 
+ else
+-CFLAGS = SUB_OPT_CFLAGS
++CFLAGS = SUB_OPT_CFLAGS -fhonour-copts
+ 
+ ifeq ($(TARGET),none)
+ canfestival: libcanfestival.o
+--- a/drivers/unix/Makefile.in
++++ b/drivers/unix/Makefile.in
+@@ -85,7 +85,7 @@ install:
+ 
+ 
+ else
+-CFLAGS = SUB_OPT_CFLAGS
++CFLAGS = SUB_OPT_CFLAGS -fhonour-copts
+ 
+ driver: libcanfestival_$(TARGET).a
+ 
+--- a/drivers/timers_unix/Makefile.in
++++ b/drivers/timers_unix/Makefile.in
+@@ -23,7 +23,7 @@
+ 
+ CC = SUB_CC
+ OPT_CFLAGS = -O2
+-CFLAGS = SUB_OPT_CFLAGS
++CFLAGS = SUB_OPT_CFLAGS -fhonour-copts
+ PROG_CFLAGS = SUB_PROG_CFLAGS
+ OS_NAME = SUB_OS_NAME
+ ARCH_NAME = SUB_ARCH_NAME