Do not force use of static libcheck.a library
Existing CMakeList forces the use of libcheck.a
when compiling for tests, however some distributions (for example Arch Linux) does not ship static libraries by default.
In order to lower the access barrier for someone trying S2OPC for the first time, it would be useful to make the use of libcheck.a
instead of libecheck.so
a Cmake option (CHECK_USE_STATIC_LIBS).