On some platforms curl would crash if no credentials were used. As such
added detection of such a use case to prevent this from happening.
Reported-by: Gisle Vanem
smb.c:398: warning: comparison of integers of different signs:
'ssize_t' (aka 'long') and 'unsigned long'
smb.c:443: warning: comparison of integers of different signs:
'ssize_t' (aka 'long') and 'unsigned long'
smb.c:322: warning: conversion to 'short unsigned int' from 'unsigned
int' may alter its value
smb.c:323: warning: conversion to 'short unsigned int' from 'unsigned
int' may alter its value
smb.c:482: warning: conversion to 'short unsigned int' from 'int' may
alter its value
smb.c:521: warning: conversion to 'unsigned int' from 'curl_off_t' may
alter its value
smb.c:549: warning: conversion to 'unsigned int' from 'curl_off_t' may
alter its value
smb.c:550: warning: conversion to 'short unsigned int' from 'int' may
alter its value
smb.c:489: warning: declaration of 'close' shadows a global declaration
smb.c:511: warning: declaration of 'read' shadows a global declaration
smb.c:528: warning: declaration of 'write' shadows a global declaration
smb.c:212: warning: unused parameter 'done'
smb.c:380: warning: ISO C does not allow extra ';' outside of a function
smb.c:812: warning: unused parameter 'premature'
smb.c:822: warning: unused parameter 'dead'
smb.c:311: warning: conversion from 'unsigned __int64' to 'u_short',
possible loss of data
smb.c:425: warning: conversion from '__int64' to 'unsigned short',
possible loss of data
smb.c:452: warning: conversion from '__int64' to 'unsigned short',
possible loss of data
smb.c:162: error: comma at end of enumerator list
smb.c:469: warning: conversion from 'size_t' to 'unsigned short',
possible loss of data
smb.c:517: warning: conversion from 'curl_off_t' to 'unsigned int',
possible loss of data
smb.c:545: warning: conversion from 'curl_off_t' to 'unsigned int',
possible loss of data
