[testsuite] Fix bb-slp-77.c for x86

[Kugan Vivekanandarajah]

This test  bb-slp-77.c  extracted  relies on the completely unrolling of the 
inner loop. However, for x86 in gcc.dg/vect/, loop is not unrolled and the 
inner loop is vectorized thus not triggering expected BB SLP 

Also noticed that the "vectorizing stmts using SLP” count is different when I 
force the loop to unroll for x86. Thus, to keep it simple, moving the test to  
gcc.target/aarch64.

Regression tested on aarch64-linux-gnu. Is this OK?

Thanks,
Kugan

0001-testsuite-Fix-bb-slp-77.c.patch
Description: 0001-testsuite-Fix-bb-slp-77.c.patch