Fix multiple issue in the testcase allocate-1.f90.

Fix multiple issue in the testcase allocate-1.f90.

1. Thomas reported in
https://gcc.gnu.org/pipermail/gcc-patches/2022-January/589039.html
that this testcase is randomly failing. The problem was fixed pool
size which was exhausted when there were a lot of threads. Fixed it
by removing pool_size trait which causes default pool size to be used
which should be big enough.

2. Array indices have been changed to check the last element in the
array.

3. Remove a redundant assignment and move some code to better match
C testcase.

libgomp/ChangeLog:

	* testsuite/libgomp.fortran/allocate-1.f90: Remove pool_size
	trait.  Test last index in w and v array.  Remove redundant
	assignment to V(1).  Move alignment checks at the end of
	parallel region.