when WEBP_USE_THREAD=1; this is necessary after:
0d1b9bc4 WEBP_DEP_LIBRARIES: use Threads::Threads
fixes:
CMake Error at WebPTargets.cmake:76 (set_target_properties):
The link interface of target "WebP::webp" contains:
Threads::Threads
but the target was not found. Possible reasons include:
* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.
Bug: webp:583
Change-Id: I19633bcceccacb95be06aa9610512127f3c288a6
Fixed: webp:583
this should be the full path to the installed headers to be added to the
client code's search path, e.g., /usr/local/include when including
<webp/decode.h>
Bug: webp:509
Change-Id: I756249876d8de421c9a33513221fb635157560ef
