libganglia: avoid slurpfile failure path on EOF
libganglia: avoid slurpfile failure path on EOF

when read returns 0 (for example in EOF), this error path shouldn't be
followed or it could lead to a bogus failure message and the unlikely
possibility that an stale errno might be EINTR and therefore trigger
a busy loop.

Reported-By: Kostas Georgiou <0db483f5859a6ffcb215284e5bacf7defcb9b0c6@atreides.org.uk>


torkelsson/monitor-core,lawrencewu/monitor-core,mjzhou/monitor-core,mjzhou/monitor-core,sdgdsffdsfff/monitor-core,NoodlesNZ/monitor-core,lawrencewu/monitor-core,phreakocious/monitor-core,sdgdsffdsfff/monitor-core,fastly/monitor-core,mjzhou/monitor-core,torkelsson/monitor-core,fastly/monitor-core,lawrencewu/monitor-core,NoodlesNZ/monitor-core,torkelsson/monitor-core,mjzhou/monitor-core,torkelsson/monitor-core,NoodlesNZ/monitor-core,NoodlesNZ/monitor-core,fastly/monitor-core,ganglia/monitor-core,lawrencewu/monitor-core,fastly/monitor-core,dmourati/monitor-core,hinesmr/monitor-core,phreakocious/monitor-core,phreakocious/monitor-core,ganglia/monitor-core,fastly/monitor-core,dmourati/monitor-core,phreakocious/monitor-core,dmourati/monitor-core,lawrencewu/monitor-core,fastly/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,ganglia/monitor-core,torkelsson/monitor-core,mjzhou/monitor-core,sdgdsffdsfff/monitor-core,phreakocious/monitor-core,dmourati/monitor-core,mjzhou/monitor-core,hinesmr/monitor-core,phreakocious/monitor-core,sdgdsffdsfff/monitor-core,torkelsson/monitor-core,ganglia/monitor-core,sdgdsffdsfff/monitor-core,hinesmr/monitor-core,fastly/monitor-core,sdgdsffdsfff/monitor-core,NoodlesNZ/monitor-core,mjzhou/monitor-core,NoodlesNZ/monitor-core,phreakocious/monitor-core,sdgdsffdsfff/monitor-core,ganglia/monitor-core,dmourati/monitor-core,lawrencewu/monitor-core,ganglia/monitor-core,lawrencewu/monitor-core,torkelsson/monitor-core,hinesmr/monitor-core,dmourati/monitor-core,ganglia/monitor-core,hinesmr/monitor-core