I am building libxslt outside of the source tree, with crypto support disabled. Unfortunately, this would fail with

libtool: link: gcc -pedantic -pipe -fno-common -W -Wall -Wcast-align -Wformat=2 -Wpointer-arith -Wundef -Waggregate-return -Wcast-qual -Wmissing-declarations -Wnested-externs -Wstrict-prototypes -march=opteron -O3 --param inline-unit-growth=400 --param large-function-growth=4000 --param max-inline-insns-single=2000 -Wall -o xsltproc xsltproc.o  ../libxslt/.libs/libxslt.a -L/tg/freeport/arch/linux64/lib ../libexslt/.libs/libexslt.a /home/cport/tmp/libxslt-build/libxslt/.libs/libxslt.a /tg/freeport/arch/linux64/lib/libxml2.a -ldl -lm
../libexslt/.libs/libexslt.a(exslt.o)(.text+0xf): In function `exsltRegisterAll':
: undefined reference to `exsltCryptoRegister'
collect2: ld returned 1 exit status
make[2]: *** [xsltproc] Error 1
make[2]: Leaving directory `/home/cport/tmp/libxslt-build/xsltproc'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/cport/tmp/libxslt-build'
make: *** [all] Error 2

The reason for this is that the source tarball contains an instantiated config file libexslt/exsltconfig.h (alongside the exsltconfig.h.in template), which happens to enable crypto support.

exsltconfig.h needs to be removed from the tarball. More specifically, libexslt/Makefile.am needs to be tweaked so that this file (as opposed to the template) is not distributed.