[Libreoffice] Disable GCC optimizations when building with --enable-symbols

[Santiago Bosio]

Hi!

When LibO is built using --enable-symbols, it still uses -O2 
optimizations, making hard to debug execution with GDB.

So, I think that it should default to -O2 on a normal build, and to -O0 
when using --enable-symbols. Don't see the point of using optimizations 
when building a version for debugging purposes.

I'm not clever enough to know what magic lines should be changed on 
autogen.sh or configure to get this done, so currently I'm exporting 
CFLAGS before calling autogen.sh and make to disable optimizations.

Perhaps, somebody with a deeper knowledge of autotools or configure 
script could change this behaviour and commit it?

Best regards,

Santiago