[NFC] Remove old README.txt under llvm/lib/Analysis/

[xgupta]

Summary

Github issue might be place to list them.
I think these two optimization oppertunities are fulfilled now.
Aleast for first testcase is not there and for second it seems fixed -
https://godbolt.org/z/KEzz4hafn

[nikic]

LGTM

llvm/lib/Analysis/README.txt

-Analysis Opportunities:
-
-//===---------------------------------------------------------------------===//
-
-In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
-ScalarEvolution expression for %r is this:
-
-  {1,+,3,+,2}<loop>
-
-Outside the loop, this could be evaluated simply as (%n * %n), however
-ScalarEvolution currently evaluates it as
-
-  (-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))
-
-In addition to being much more complicated, it involves i65 arithmetic,
-which is very inefficient when expanded into code.
-
-//===---------------------------------------------------------------------===//
-
-In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,
-
-ScalarEvolution is forming this expression:
-
-((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))
-
-This could be folded to
-
-(-1 * (trunc i64 undef to i32))
-
-//===---------------------------------------------------------------------===//