of-signal: update to v1.4.2 * src/of-signal.mk: update version, checksum * src/of-signal-1-deprecated-warnings.patch: removed * src/of-signal-2-error_state.patch: removed * dist-files.mk: update for removed files (grafted from 4fcf129648a7b2ab0f6874a028f63cab4d0e2a0e)

#include <iostream>
#include <cpp/poppler-version.h>

int main(int argc, char *argv[])
{
    (void)argc;
    (void)argv;

    std::cout << "Poppler version: " << poppler::version_string() << std::endl;

    return 0;
}