Could not build on Ubuntu xenial

[tdelev]

When trying to install the gem on Ubuntu 16.04 LTS with all the requirements installed I'm getting this error:

...
checking for mtex2MML.h in /var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical/mtex2MML/src... yes
creating Makefile

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/mathematical-1.6.7/mkmf.log

current directory: /var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical
make "DESTDIR=" clean

current directory: /var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical
make "DESTDIR="
compiling cairo_callbacks.c
compiling lasem_overrides.c
In file included from /usr/include/string.h:630:0,
                 from /var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical/mtex2MML/src/../deps/uthash/uthash.h:29,
                 from /var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical/mtex2MML/src/environment.h:4,
                 from /var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical/mtex2MML/src/mtex2MML.h:12,
                 from lasem_overrides.c:5:
/var/lib/gems/2.3.0/gems/mathematical-1.6.7/ext/mathematical/mtex2MML/src/../deps/uthash/../strdup/strdup.h:24:1: error: expected identifier or ‘(’ before ‘__extension__’
 strdup(const char *str);
 ^
Makefile:239: recipe for target 'lasem_overrides.o' failed
make: *** [lasem_overrides.o] Error 1

make failed, exit code 2

Gem files will remain installed in /var/lib/gems/2.3.0/gems/mathematical-1.6.7 for inspection.
Results logged to /var/lib/gems/2.3.0/extensions/x86_64-linux/2.3.0/mathematical-1.6.7/gem_make.out

[tdelev]

It was a duplicate to #64

[gjtorikian]

Sorry! I'll release an update that fixes this right now!