cppu: Avoid uno_direct_getEnvironment() indirection.

"UNO_ENV_SUBST:" should not be used.

Change-Id: If23b174de792cd69dc79e70dd8f5e8a31badb96d
Let's have a static variable for getenv("UNO_ENV_LOG").

Change-Id: Id382726b86726515a9ae3017c11fad0420136a4c
Remove unused SvXMLExport::mbEnableExperimentalOdfExport.

Change-Id: Ib2dbc4af73394c9c35a7f273fd8966b91ac3eb84
Use static for this getenv call too.

Change-Id: Ieb8dd13763c6d5e6d30ce641683de79d89d135df