Libprocess: Replaced $(top_srcdir) with $(srcdir) in Makefile.am.
Libprocess: Replaced $(top_srcdir) with $(srcdir) in Makefile.am.

The variable $(top_srcdir) causes compilation failure if the Makefile is
generated by top-level configure script instead of libprocess-specific
configure script.

Also replaced ${abs_top_builddir} with ${abs_builddir}. This is used to
compute path to ssl-client binary.

Review: https://reviews.apache.org/r/46530

kaysoky/mesos,Gilbert88/mesos,zmalik/mesos,kaysoky/mesos,andschwa/mesos,abudnik/mesos,asamerh4/mesos,zmalik/mesos,dforsyth/mesos,yuquanshan/customizedMesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,neilconway/mesos,gsantovena/mesos,Gilbert88/mesos,neilconway/mesos,chhsia0/mesos,reneploetz/mesos,craimbert/mesos,reneploetz/mesos,andschwa/mesos,gsantovena/mesos,kaysoky/mesos,chhsia0/mesos,asamerh4/mesos,chhsia0/mesos,dforsyth/mesos,craimbert/mesos,jpeach/mesos,jpeach/mesos,reneploetz/mesos,yuquanshan/customizedMesos,kaysoky/mesos,andschwa/mesos,dforsyth/mesos,Gilbert88/mesos,Aman-Jain-14/customizedMesos,jpeach/mesos,dforsyth/mesos,yuquanshan/customizedMesos,neilconway/mesos,Aman-Jain-14/customizedMesos,abudnik/mesos,Gilbert88/mesos,craimbert/mesos,chhsia0/mesos,craimbert/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,chhsia0/mesos,reneploetz/mesos,andschwa/mesos,asamerh4/mesos,Gilbert88/mesos,andschwa/mesos,verizonlabs/mesos,zmalik/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,jpeach/mesos,gsantovena/mesos,asamerh4/mesos,chhsia0/mesos,abudnik/mesos,craimbert/mesos,zmalik/mesos,verizonlabs/mesos,verizonlabs/mesos,reneploetz/mesos,gsantovena/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,kaysoky/mesos,jpeach/mesos,dforsyth/mesos,verizonlabs/mesos,dforsyth/mesos,craimbert/mesos,verizonlabs/mesos,abudnik/mesos,abudnik/mesos,yuquanshan/customizedMesos,andschwa/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,gsantovena/mesos,chhsia0/mesos,abudnik/mesos,reneploetz/mesos,neilconway/mesos,Gilbert88/mesos,verizonlabs/mesos,gsantovena/mesos,jpeach/mesos,andschwa/mesos,zmalik/mesos,craimbert/mesos,neilconway/mesos,zmalik/mesos,dforsyth/mesos,Gilbert88/mesos,gsantovena/mesos,asamerh4/mesos,jpeach/mesos,asamerh4/mesos,reneploetz/mesos,kaysoky/mesos,zmalik/mesos,kaysoky/mesos,abudnik/mesos