>./ggsci
Answer: In searching for an answer to this, I was able to identify that this DLL is a part of the Microsoft Visual C++ 2010 Redistribution Package (x64) (download here). After installing the package, the GGSCI command will run successfully.
GGSCI> create subdirs
Creating subdirectories under current directory /home/informix/ogg
Parameter files /home/informix/ogg/dirprm: already exists
Report files /home/informix/ogg/dirrpt: created
Checkpoint files /home/informix/ogg/dirchk: created
Process status files /home/informix/ogg/dirpcs: created
SQL script files /home/informix/ogg/dirsql: created
Database definitions files /home/informix/ogg/dirdef: created
Extract data files /home/informix/ogg/dirdat: created
Temporary files /home/informix/ogg/dirtmp: created
Credential store files /home/informix/ogg/dircrd: created
Masterkey wallet files /home/informix/ogg/dirwlt: created
Dump files /home/informix/ogg/dirdmp: created
Step 3: Connect to Source Database
GGSCI (ogg-1.pssa.us.oracle.com) 1> dblogin sourcedb syscdcv1
2013-10-25 11:42:23 INFO OGG-03036 Database character set identified as ISO-8859-1. Locale: en_US.
2013-10-25 11:42:23 INFO OGG-03037 Session character set identified as UTF-8.
Successfully logged into database.
Step 4: Configure and Start the Oracle GoldenGate Manager
GGSCI> edit param mgr
PORT 15000
DYNAMICPORTLIST 15010-15020
PURGEOLDEXTRACTS ./dirdat/*, USECHECKPOINTS
AUTORESTART ER *
GGSCI> start mgr
Manager started.
GGSCI> info mgr
Manager is running (IP port brown.oracle.jp.15000, Process ID 18105).
Now, the Oracle GoldenGate is ready for use.