* test/src/comp-tests.el: Rework last patch

* test/src/comp-tests.el: Rework last patch

Move `require`s out of `eval-when-compile` if the functions are called
at run-time.
Don't use #' to quote symbols (i.e. at those places where a lambda
expression couldn't be used).
Don't pre-load comp-test-45603.el and comp-test-pure.el any more.

(comp-deftest pure): Use `declare-function` after loading `comp-test-pure.el`
to silence the byte-compiler.