I'm having trouble installing the R package expm on my Heroku instance.

I get the following errors:

```
* installing *source* package ‘expm’ ...
** package ‘expm’ successfully unpacked and MD5 sums checked
** libs
gcc -std=gnu99 -I/app/vendor/R/lib/R/include -DNDEBUG  -I/usr/local/include    -fpic  -g -O2  -c R_dgebal.c -o R_dgebal.o
In file included from locale.h:4:0,
                 from expm.h:10,
                 from R_dgebal.c:4:
R_dgebal.c: In function ‘ebal_type’:
locale.h:5:19: error: ‘LC_MESSAGES’ undeclared (first use in this function)
 #define _(String) dgettext ("expm", String)
                   ^
R_dgebal.c:11:8: note: in expansion of macro ‘_’
  error(_("argument type='%s' must be a character string of string length 1"),
        ^
locale.h:5:19: note: each undeclared identifier is reported only once for each function it appears in
 #define _(String) dgettext ("expm", String)
                   ^
R_dgebal.c:11:8: note: in expansion of macro ‘_’
  error(_("argument type='%s' must be a character string of string length 1"),
        ^
R_dgebal.c: In function ‘R_dgebal’:
locale.h:5:19: error: ‘LC_MESSAGES’ undeclared (first use in this function)
 #define _(String) dgettext ("expm", String)
                   ^
R_dgebal.c:28:8: note: in expansion of macro ‘_’
  error(_("invalid 'x': not a numeric (classical R) matrix"));
        ^
make: *** [R_dgebal.o] Error 1
ERROR: compilation failed for package ‘expm’
* removing ‘/app/vendor/R/lib/R/library/expm’
ERROR: dependency ‘expm’ is not available for package ‘msm’
* removing ‘/app/vendor/R/lib/R/library/msm’
ERROR: dependency ‘msm’ is not available for package ‘ltm’
* removing ‘/app/vendor/R/lib/R/library/ltm’

```

I'm using the R buildpack and not sure exactly what's causing the error.

Thanks!

I'm planning on installing a R package a friend wrote, but the package expm which it depends on won't install.

From sessionInfo():

```
> sessionInfo()
R version 3.1.2 (2014-10-31)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base   

```

The buildpack installs R using this script: <https://github.com/virtualstaticvoid/heroku-buildpack-r/blob/master/support/build-r>