configure: bugfix in check_boost_thread_libs()

Hi Jae-hyeon,

sorry to spam you, but I think there is a tiny bug in your recent
configure script commit.  You wrote

  if [ -z "x$found_lib" ]; then

This condition will never be true, because of the `x' in the string.  :)

Best,
Alex
Merge branch 'master' of ssh://pktlogin.phy.tu-dresden.de/soft/users/theory/FlexibleSUSY
convert test file into unix format
get more information about the platform we have
look for libraries in Debian multiarch directories as well
check if libpthread is available
put the spectrum generator class into a separate file
put the low-energy model spectrumg generator into a separate file
rename runner to spectrum_generator
do not manipulate SARAH functions to avoid problems with other modules
Fix IsHermitian[]

Apply //. instead of /. to both m[[i,k]] and op[m[[k,i]]].  Also,
check that the diagonal elements are real.
remove comments in SLHA files because they will appear in the output
merge bugfix from upstream
merge utils.h from upstream/nmssm2
remove unused functions
merge helper function from upstream/nmssm2
merge optimizations from upstream/nmssm2
merge def.{h,cpp} from upstream/nmssm2
decrease the default precision to 10^-4 which is the default in Softsusy
add missing include (needed for ToValarray())