Fix compilation errors

[gholmann16]

These two commits fix errors in compiling on:

• Ubuntu 14, which requires you to include cstring in order to use memcpy
• Alpine Linux, which when I attempt to compile the source code requires me to get rid of the __BEGIN_DECLS and __END_DECLS statements. These symbols also seem to be substandard according to the libtool manual: https://www.gnu.org/software/libtool/manual/html_node/C-header-files.html (check footnotes)

[TheAssassin]

Thanks!