Link to Swift libraries for CI tests

[seabaylea]

The libdispatch CI test failed for #100:
#100

Due to the following linkage issues when building the tests:

../src/.libs/libdispatch.so: undefined reference to `_TTSgq5SiSis10ComparablesSis11_Strideables___TFVs14CountableRangeg8endIndexx'
../src/.libs/libdispatch.so: undefined reference to `_TTSgq5SiSis10ComparablesSis11_Strideables___TFVs14CountableRangeg10startIndexx'
../src/.libs/libdispatch.so: undefined reference to `_TTSgq5SiSis10ComparablesSis11_Strideables___TFVs14CountableRangeCfT15uncheckedBoundsT5lowerx5upperx__GS_x_'

Those symbols appear in libswiftSwiftOnoneSupport. Additionally after adding that library to the linkage flags, the tests fail to find the Swift libraries during test execution, which can be fixed by adding the Swift library directory to the RPATH.