Update ofSystemUtils.cpp

changes so master can build on ARM LINUX
Update ofSystemUtils.cpp

TARGET_LINUX_ARM-> TARGET_RASPBERRY_PI
Merge pull request #2988 from danthemellowman/patch-8

Update ofSystemUtils.cpp

Just tested this and it allows the RPi to compile again. It won't effect any other platforms so merging
smaller fix for RPi compiling issue with XInitThreads
smaller fix for RPi not being able to compile with XInitThreads
permissions fix
remove RPi ifdefs
Fix the problem that frame rate becomes slower than the specified value.
install_dependencies debian & ubuntu, gtk3 package was wrong
Merge branch 'master' of github.com:openframeworks/openFrameworks
kiss_fft.h: reaklines
ofTrueTypeFont: initialize all members in constructor
Merge pull request #2993 from nistetsurooy/more-precise-fps

Fix the problem that frame rate becomes slower than the specified value.
ofSetFramerate: more explanative variable names and comments + CHANGELOG
fix last ocmmit
linux: more precise timming function through monotonic clock
Merge branch 'master' of https://github.com/openframeworks/openFrameworks.git into rexgo