libtool handles "portability" on Linux but does not even handle basic ld features like -L and -R options correctly.
All a bit more complex projects have problems compiling on Solaris because usually -R is not used and the linked binaries thus will not find their libraries and this is definitely not a Solaris caused problem.
BTW: even "autotools" is a step from autoconf into the wrong direction. Autoconf (as documented by the FSF is based on self modifying makefiles - a technique from the 1970s). What the FSF calls "automake" is definitely not an automake program but something that makes people believe that it will create portable makefiles but does not. What it really does is to propagate code that depends on bugs and extensions of gmake.