### This is how I built and tested, it's a bit crude.
mkdir ~/sandbox
cd ~/sandbox
hg clone https://hg.mozilla.org/projects/nspr
hg clone https://hg.mozilla.org/projects/nss
git clone git@github.com:dogtagpki/jss.git

####### Setup Environment Variables
export JAVA_HOME=/etc/alternatives/java_sdk_1.8.0_openjdk
export USE_64=1
export CHECK_DEPRECATION=1

####### Build Before #######
cd ~/jss
## Build the simple way just to take care of nspr, nss, jss
make clean all
Build again so that only jss shows up
script -c 'make clean all' typescript.build.before
grep warning: typescript.build.before > warnings.before
wc -l warnings.before
## I got 45 warnings
script -c 'make test_jss' typescript.tests.before
# 33/33 pass
####### Build After #######
## Apply the patch from the pull request #26
# https://github.com/dogtagpki/jss/pull/26/commits/5fe56ad33308c8a0c15131947c2544c03860da57
# add .patch to that URL and it look like patch
# https://github.com/dogtagpki/jss/commit/5fe56ad33308c8a0c15131947c2544c03860da57.patch
# save it to the directory above and apply it with 
git am ../5fe56ad33308c8a0c15131947c2544c03860da57.patch
# doing meld . will show you "1 unpushed commit"
# now build and performs the checks we did before
script -c 'make clean all' typescript.build.after
grep warning: typescript.build.after > warnings.after
script -c 'make test_jss' typescript.tests.after
# 33/33 pass
####### compare after against before
## I got 45 this time
## It's hard to visually compare warnings.before and warnings.after as
## they don't have the same sequence, you can sort them and that helps a bit
sort warnings.before > sorted.warnings.before
sort warnings.after > sorted.warnings.after
# Now the visual comparison
meld sorted.warnings.before sorted.warnings.after
## Not as good as one would have liked but better than unsorted
## In many entries the line numbers will be different on account of the patch
diff --unified sorted.warnings.before sorted.warnings.after > warnings.diff
### I bet you have a better method than this one