Fix #
3148124: sipe segfaults during login on Solaris
Because config.h was not included in sip-sec-ntlm.c, macro
HAVE_LANGINFO_CODESET was never defined, resulting in "ANSI_X3.4-1968"
to be always used instead of system codeset at sip_sec_init__ntlm().
iconv on Solaris does not know this alias for ASCII, so g_iconv_open()
calls in sip_sec_init__ntlm() failed and initialized conversion
descriptors with meaningless values.
* included config.h
* used "US-ASCII" as default codeset when compiling for Solaris