This patch adds lower-bound and upper-bound to num_teams clause
according to OpenMP 5.1 specification. The initial number of teams
created is implementation defined, but it will be greater than or
equal to lower-bound and less than or equal to upper-bound. If
num_teams clause is not specified, the number of teams created is
implementation defined, but it will be greater or equal to 1.
Differential Revision: https://reviews.llvm.org/D95820
Implement GOMP_teams_reg() function which enables GOMP support of the
standalone teams construct. The GOMP_parallel* functions were modified
to call __kmp_fork_call() unconditionally so that the teams-specific
code could be reused within __kmp_fork_call() instead of reproduced
inside the GOMP_* functions.
Differential Revision: https://reviews.llvm.org/D87167
