Wow.
Some how I missed your followup on this thread and just came across it today.
The error from Make is when trying to make the boinc database, which requires mysql.
You probably just wanted to make the client, so you pass --disable-server to configure and then cd into client and type make.
To add optimization flags, you can either set environment variables with the flags or pass them to configure.
If you don't understand all that then you probably should not mess with optimization.
in tcsh
setenv C_FLAGS "-O3 -mcpu=G4 -mtune=G4 -faltivec"
etc

or to pass to configure
./configure --disable-server C_FLAGS="-O3 -mcpu=G4 -mtune=G4 -faltivec" CPP_FLAGS="-O3 -mcpu=G4 -mtune=G4 -faltivec"

There are many different flags within the Makefiles that can use the optimization stuff.
It is best to look through the one in the client directory to see what they are.