Signedness problems with libfreeipmi

[jimklimov]

According to recent builds like the cases linked below, it may be that different distributions have different data types for fields in libfreeipmi structures - so in some builds but far from all, mismatches against variable types used by NUT are reported.

• http://buildbot.networkupstools.org/public/nut/builders/Ubuntu-trusty-x64-clang/builds/573/steps/compile/logs/warnings%20%287%29

../../drivers/nut-libfreeipmi.c:380:4: warning: passing 'int *' to parameter of type 'unsigned int *' converts between pointers to integer types with different sign [-Wpointer-sign]
../../drivers/nut-libfreeipmi.c:381:4: warning: passing 'int *' to parameter of type 'unsigned int *' converts between pointers to integer types with different sign [-Wpointer-sign]
../../drivers/nut-libfreeipmi.c:382:4: warning: passing 'int *' to parameter of type 'unsigned int *' converts between pointers to integer types with different sign [-Wpointer-sign]
../../drivers/nut-libfreeipmi.c:383:4: warning: passing 'int *' to parameter of type 'unsigned int *' converts between pointers to integer types with different sign [-Wpointer-sign]

• http://buildbot.networkupstools.org/public/nut/builders/Ubuntu-trusty-x64/builds/570/steps/compile/logs/warnings%20%284%29

../../drivers/nut-libfreeipmi.c:397:4: warning: pointer targets in passing argument 8 of 'ipmi_fru_parse_multirecord_power_supply_information' differ in signedness [-Wpointer-sign]
../../drivers/nut-libfreeipmi.c:397:4: warning: pointer targets in passing argument 9 of 'ipmi_fru_parse_multirecord_power_supply_information' differ in signedness [-Wpointer-sign]
../../drivers/nut-libfreeipmi.c:397:4: warning: pointer targets in passing argument 10 of 'ipmi_fru_parse_multirecord_power_supply_information' differ in signedness [-Wpointer-sign]
../../drivers/nut-libfreeipmi.c:397:4: warning: pointer targets in passing argument 11 of 'ipmi_fru_parse_multirecord_power_supply_information' differ in signedness [-Wpointer-sign]

[jimklimov]

Should be fixed by #1181 and #1179

Dup of #1175