Fixing uninitialized variable bug in blocking and PH joins

probe_side_eos_ was uninitialized at the first GetNext call and that was causing
random behavior. Also, PHJ GetNext() should init eos.

Change-Id: I586dd625cead11abac12cc007b16769a107b5746
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3984
Reviewed-by: Ippokratis Pandis <ipandis@cloudera.com>
Tested-by: jenkins
Implemented instruction counter for LLVM IR.

Enabled by passing flag print_llvm_ir_instruction_count to impalad.

Sample output:

===-------------------------------------------------------------------------===
                         ... Instruction Counts ...
===-------------------------------------------------------------------------===
2  Binary                             Number of Binary instructions.
4  Other                              Number of Other instructions.
5  Terminator                         Number of Terminator instructions.
===-------------------------------------------------------------------------===
                              ... Totals ...
===-------------------------------------------------------------------------===
5  Total Blocks                       Number of Blocks in module.
1  Total Functions                    Number of Functions in module.
11 Total Instruction                  Number of Total Instructions.

Change-Id: I565d2bf8e084c71448ee312e38b6dc7a96cc20b6
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/3603
Reviewed-by: Paden Tomasello <paden.tomasello@cloudera.com>
Tested-by: jenkins