yajl: Bump version to 2.1.0

Remove 0001-math-link.patch as some added code render it useless.
Rework 0002-cmake-disable-shared-library-build-when-BUILD_SHARED.patch
because it did not apply anymore.
This patch is already in a PR upstream.

Add 0001-cmake-uClibc-Fix-missing-libm-for-tests.patch, to fix a build
error with uClibc toolchain.
This has been sent upstream:
https://github.com/lloyd/yajl/pull/184



Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>