Fix some build warnings and errors on linux

indra/llcommon/is_approx_equal_fraction.h

indra/llcommon/llcommonprecompiled.h

indra/llcommon/llstring.h

indra/llcommon/llthread.cpp

indra/llimage/llimageworker.cpp

indra/newview/llagentcamera.cpp

indra/newview/lloutfitgallery.cpp

indra/newview/llpanelobject.cpp

indra/newview/llstatusbar.cpp

indra/newview/llviewerprecompiledheaders.h