Initialize log4cplus early if possible.

Use GCC constructor function attribute when it is present.
Check for init_priority GCC variable attribute and use it.
Fix log level string constants initialization issue. (SF bug #303)
Based on patch by: Ray Logel
Bump log4cplus library's libtool revision number.
add setCurrentThreadName(,2) to modify the thread name
Merge pull request #2 from sfzhang/1.1.x

add setCurrentThreadName(,2) to modify the thread name
threads.cxx: Use init priority for thread_name and thread_name2.
Mention Zhang Shengfa.
Merge pull request #40 from wilx/1.1.x

Merge.