[packages] i2c-tools: fix TARGET_CPPFLAGS

Fixes #13546 and #13857.

Signed-off-by John Vogel <jvogel4@stny.rr.com>

git-svn-id: svn://svn.openwrt.org/openwrt/packages@39069 3c298f89-4303-0410-b956-a3cf2f4a3e73
[packages] i2c-tools: update to r6204

Signed-off-by: Luka Perkov <luka@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/packages@39070 3c298f89-4303-0410-b956-a3cf2f4a3e73