Net-SNMP was crashing (signal 11) on every operation despite fork isolation.
The issue was that init_snmp() tries to load MIB files by default, which can
cause crashes if MIB files are missing, corrupted, or incompatible.
Since we only use numeric OIDs (e.g., "1.3.6.1.2.1.1.1.0"), we don't need
MIB name resolution at all. This change explicitly disables MIB loading in
the child process by:
1. Setting MIBS and MIBDIRS environment variables to empty
2. Calling netsnmp_set_mib_directory("") to disable MIB directory search
3. These must happen BEFORE calling init_snmp()
This should fix the persistent SIGSEGV crashes in SNMP operations.
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>