[Libguestfs] hivex: Exported foreign symbols in libhivex.so.0.0.0

[TJ]

The symbols file generated in the Debian package to aid the package
maintainer automatically detect future changes shows internal library
and helper function names, whereas it should only be exporting hivex_*
function names. This page may help with this:

http://gcc.gnu.org/wiki/Visibility

Symbols:

 asnprintf at Base 1.2.1
 c_isalnum at Base 1.2.1
 c_isalpha at Base 1.2.1
 c_isascii at Base 1.2.1
 c_isblank at Base 1.2.1
 c_iscntrl at Base 1.2.1
 c_isdigit at Base 1.2.1
 c_isgraph at Base 1.2.1
 c_islower at Base 1.2.1
 c_isprint at Base 1.2.1
 c_ispunct at Base 1.2.1
 c_isspace at Base 1.2.1
 c_isupper at Base 1.2.1
 c_isxdigit at Base 1.2.1
 c_tolower at Base 1.2.1
 c_toupper at Base 1.2.1
 exit_failure at Base 1.2.1
 full_read at Base 1.2.1
 full_write at Base 1.2.1
 printf_fetchargs at Base 1.2.1
 printf_parse at Base 1.2.1
 program_name at Base 1.2.1
 safe_read at Base 1.2.1
 safe_write at Base 1.2.1
 set_program_name at Base 1.2.1
 vasnprintf at Base 1.2.1
 xstrtol at Base 1.2.1
 xstrtol_fatal at Base 1.2.1
 xstrtoll at Base 1.2.1
 xstrtoul at Base 1.2.1
 xstrtoull at Base 1.2.1