[minor fix] Replaced a malloc followed by the zeroing of the structure with a calloc.
[minor fix] Replaced a malloc followed by the zeroing of the structure with a calloc.

This offers a little speed boost and, in case someone changes the z_stream structure, there won't be any corruption of the data if variables aren't initialized properly.
ganglia/monitor-core,lawrencewu/monitor-core,phreakocious/monitor-core,NoodlesNZ/monitor-core,sdgdsffdsfff/monitor-core,torkelsson/monitor-core,phreakocious/monitor-core,fastly/monitor-core,lawrencewu/monitor-core,mjzhou/monitor-core,mjzhou/monitor-core,lawrencewu/monitor-core,lawrencewu/monitor-core,ganglia/monitor-core,ganglia/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,torkelsson/monitor-core,fastly/monitor-core,torkelsson/monitor-core,NoodlesNZ/monitor-core,sdgdsffdsfff/monitor-core,sdgdsffdsfff/monitor-core,mjzhou/monitor-core,torkelsson/monitor-core,fastly/monitor-core,phreakocious/monitor-core,NoodlesNZ/monitor-core,NoodlesNZ/monitor-core,mjzhou/monitor-core,lawrencewu/monitor-core,ganglia/monitor-core,fastly/monitor-core,torkelsson/monitor-core,phreakocious/monitor-core,fastly/monitor-core,lawrencewu/monitor-core,NoodlesNZ/monitor-core,mjzhou/monitor-core,ganglia/monitor-core,sdgdsffdsfff/monitor-core,sdgdsffdsfff/monitor-core,lawrencewu/monitor-core,torkelsson/monitor-core,phreakocious/monitor-core,mjzhou/monitor-core,phreakocious/monitor-core,sdgdsffdsfff/monitor-core,torkelsson/monitor-core,mjzhou/monitor-core,sdgdsffdsfff/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,fastly/monitor-core,fastly/monitor-core,phreakocious/monitor-core,ganglia/monitor-core