Tests for weighted merge of instrumented profiles.

1- Merge the foo and bar profiles with unity weight and verify the combined output
RUN: llvm-profdata merge --instr %p/Inputs/weight-instr-bar.profdata:1 %p/Inputs/weight-instr-foo.profdata:1 -o %t
RUN: llvm-profdata show --instr -all-functions %t | FileCheck %s --check-prefix=WEIGHT1
WEIGHT1: Counters:
WEIGHT1:   usage:
WEIGHT1:     Hash: 0x0000000000000000
WEIGHT1:     Counters: 1
WEIGHT1:     Function count: 0
WEIGHT1:   foo:
WEIGHT1:     Hash: 0x000000000000028a
WEIGHT1:     Counters: 3
WEIGHT1:     Function count: 866988873
WEIGHT1:   bar:
WEIGHT1:     Hash: 0x000000000000028a
WEIGHT1:     Counters: 3
WEIGHT1:     Function count: 866988873
WEIGHT1:   main:
WEIGHT1:     Hash: 0x7d31c47ea98f8248
WEIGHT1:     Counters: 60
WEIGHT1:     Function count: 2
WEIGHT1: Functions shown: 4
WEIGHT1: Total functions: 4
WEIGHT1: Maximum function count: 866988873
WEIGHT1: Maximum internal block count: 267914296

2- Merge the foo and bar profiles with weight 3x and 5x respectively and verify the combined output
RUN: llvm-profdata merge --instr %p/Inputs/weight-instr-bar.profdata:3 %p/Inputs/weight-instr-foo.profdata:5 -o %t
RUN: llvm-profdata show --instr -all-functions %t | FileCheck %s --check-prefix=WEIGHT2
WEIGHT2: Counters:
WEIGHT2:   usage:
WEIGHT2:     Hash: 0x0000000000000000
WEIGHT2:     Counters: 1
WEIGHT2:     Function count: 0
WEIGHT2:   foo:
WEIGHT2:     Hash: 0x000000000000028a
WEIGHT2:     Counters: 3
WEIGHT2:     Function count: 4334944365
WEIGHT2:   bar:
WEIGHT2:     Hash: 0x000000000000028a
WEIGHT2:     Counters: 3
WEIGHT2:     Function count: 2600966619
WEIGHT2:   main:
WEIGHT2:     Hash: 0x7d31c47ea98f8248
WEIGHT2:     Counters: 60
WEIGHT2:     Function count: 8
WEIGHT2: Functions shown: 4
WEIGHT2: Total functions: 4
WEIGHT2: Maximum function count: 4334944365
WEIGHT2: Maximum internal block count: 1339571480

3- Bad merge: foo and bar profiles with invalid weights
RUN: not llvm-profdata merge --instr %p/Inputs/weight-instr-bar.profdata:3 %p/Inputs/weight-instr-foo.profdata:-5 -o %t.out 2>&1 | FileCheck %s --check-prefix=ERROR3
ERROR3: error: Input weight must be a positive integer.