[pdf-devel] Check for host endianness at configure level

[Aleksander Morgado]

Hi all,

I included a check for the host endianness at configure level and a 
`PDF_IS_BIG_ENDIAN' definition to be included in config.h. Also updated 
the text module implementation accordingly.

BTW, can anyone run the unit tests for the text module in a Big Endian 
system?

-Aleksander