[Test] Remove obsolete test.
The FIXME of this test case has been addressed in r335084/r338800. Its
execution still does not succeed because of multiple syntax errors.
First, the "clang" namespace is missing on each of the 4 pragmas.
Second, the pragma for defining the vector width is "vectorize_width(4)"
instead of "vectorize(4)". Third, the pragma for defining the interleave
factor is "interleave_count(8)" instead of "interleave(8)".
The file was already using the wrong syntax when added in
r210925 2014-06-13. The file ast-print-pragmas.cpp already checks for
the correct pragma order, making this test redundant even if fixed.
Differential Revision: https://reviews.llvm.org/D60749