Backport #8813

Create Complex.java

Class for Complex numbers and simple operations on them.
(cherry picked from commit dd2cec8fd8ab5f094def189e6dd891632d59e9cc)

Update PerfBLAS.java

Change the mandel method to make use of the Complex type removing the manual inlining and strength reduction of complex number operations.
(cherry picked from commit fc3223381bcef77132b693720dca7daa7b424ffb)

Update Complex.java

(cherry picked from commit ed5a00b3d4a4a1f8f93b63314ea952ac5108073e)

Update PerfBLAS.java
(cherry picked from commit a6e8946ca9874d68a0a3be83b48a98de018f4683)