Add check for LDAP filter overflow, and exit cleanly. #606

Job	Run time
Empty APLOGNO() test	55s
Default	3m 20s
All-static modules	3m 25s
Prefork MPM, all-modules (except cgid)	4m 30s
Worker MPM, all-modules	4m 22s
Shared MPMs, all-modules	4m 3s
Event MPM, all-modules, mod_cgid only	4m 21s
Event MPM, all-modules, no CMSG_DATA	4m 8s
Default, all-modules + install	4m 13s
Default, all-modules, random test order	4m 23s
GCC 10 maintainer-mode w/-Werror, install + VPATH	3m 5s
All-modules, APR 1.7.4, APR-util 1.6.3	6m 10s
APR 1.8.x, APR-util 1.7.x	5m 46s
Pool-debug	5m 35s
Shared MPMs (event), pool-debug, SSL/TLS variants	9m 12s
Shared MPMs (worker), pool-debug, SSL/TLS variants	8m 44s
Shared MPMs (prefork), pool-debug, SSL/TLS variants	9m 18s
litmus WebDAV tests	2m 6s
litmus WebDAV tests, APR trunk, LMDB	2m 15s
Regenerate ap_expr	4m 15s
APR 1.7.4, APR-util 1.6.3, LDAP	5m 56s
APR trunk thread debugging	4m 28s
UBSan	4m 46s
ASan	6m 9s
ASan, pool-debug	6m 50s
HTTP/2 test suite	11m 41s
MOD_TLS test suite	5m 5s
	2h 19m 1s

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