I found two issues with the cl_load fuzz targets, one of which impacts
the scanfile and scanmap fuzz targets:
1. We were defining the preprocessor definitions incorrectly using
"SCAN_TARGETS" instead of "TARGET" in unit_tests/CMakeLists.txt.
For the scan fuzz targets this meant it wasn't properly defining
unique settings for each compiled target.
For the cl_load fuzz target it's worse, it wasn't setting the
database file name correctly which means it rejected the filenames
entirely for not having a legitimate suffix.
2. We were pre-compiling the engine before loading signatures.
You can't load sigs for an engine that's already compiled, so this
would also fail right away without trying to load any sigs.
