Enable skipping minimization with an env var (#4526)

This enables a job or fuzzer config to disable minimization with an
environment variable. We can specify this at the additional environment
variables of particular fuzzers like Binaryen, that don't work well with
Clusterfuzz' built-in minimization attempts.

Bug: https://crbug.com/380264190

Author: mi-ac

src/clusterfuzz/_internal/system/environment.py

@@ -695,9 +695,11 @@ def get_engine_for_job(job_name=None):
 def is_minimization_supported():
   """Return True if the current job supports minimization.
 
-  Currently blackbox-fuzzer jobs or libfuzzer support minimization.
+  Currently blackbox-fuzzer jobs or libfuzzer support minimization, unless
+  skipped using the SKIP_MINIMIZATION environment variable.
   """
-  return not is_engine_fuzzer_job() or is_libfuzzer_job()
+  skipped = get_value('SKIP_MINIMIZATION', False)
+  return not skipped and (not is_engine_fuzzer_job() or is_libfuzzer_job())
 
 
 def is_posix():