Make it possible to work with spicy-plugin bundled with zeek.

zkg.meta

@@ -3,5 +3,5 @@ summary = Spicy-based analyzer for the DNS protocol
 description = Spicy-based analyzer for the DNS protocol.
 script_dir = analyzer
 plugin_dir = build/spicy-modules
-build_command = unset -v CXX CXXFLAGS LD LDFLAGS && mkdir -p build && cd build && SPICYZ=%(package_base)s/spicy-plugin/build/bin/spicyz cmake .. && cmake --build .
+build_command = unset -v CXX CXXFLAGS LD LDFLAGS && mkdir -p build && cd build && SPICYZ=$(command -v spicyz || %(package_base)s/spicy-plugin/build/bin/spicyz) cmake .. && cmake --build .
 test_command = unset -v CXX CXXFLAGS LD LDFLAGS && cd tests && PATH=$(zkg config plugin_dir)/packages/spicy-plugin/bin:$PATH btest -d -j $(nproc)