Some basic tests for supplementing instrumentation profile with sample profile
with flattening.

Test bar.cc:bar's counters will be set to PseudoHot.
RUN: llvm-profdata merge \
RUN:     -supplement-instr-with-sample=%p/Inputs/flatten_sample.proftext \
RUN:     %p/Inputs/flatten_instr.proftext -o %t
RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FLATTEN

FLATTEN:  foo:
FLATTEN-NEXT:    Hash: 0x0000000000000457
FLATTEN-NEXT:    Counters: 5
FLATTEN-NEXT:    Block counts: [10000, 50, 2000, 40, 6000]
FLATTEN:  bar.cc;bar:
FLATTEN-NEXT:    Hash: 0x00000000000008ae
FLATTEN-NEXT:    Counters: 10    <PseudoHot>
FLATTEN-NOT:  goo: