[LLVM] Update AliasAnalysis maintainers (#120447)

Currently hfinkel is listed as the AliasAnalysis maintainer, but I
believe he hasn't been actively working on LLVM in the last couple of
years, so I'd like to update this information.

I'd like to nominate fhahn and myself as the new maintainers for AA.
While here, I'd also like to nominate alinas as the maintainer for
MemorySSA.

Author: nikic

llvm/Maintainers.md

@@ -23,8 +23,10 @@ llvm@npopov.com, npopov@redhat.com (email), [nikic](https://github.com/nikic) (G
 
 #### AliasAnalysis
 
-Hal Finkel \
-hfinkel@anl.gov (email), [hfinkel](https://github.com/hfinkel) (GitHub)
+Nikita Popov \
+llvm@npopov.com, npopov@redhat.com (email), [nikic](https://github.com/nikic) (GitHub), nikic (Discourse) \
+Florian Hahn \
+flo@fhahn.com (email), [fhahn](https://github.com/fhahn) (GitHub)
 
 #### Attributor, OpenMPOpt
 
@@ -73,6 +75,11 @@ quentin.colombet@gmail.com (email), [qcolombet](https://github.com/qcolombet) (G
 Florian Hahn \
 flo@fhahn.com (email), [fhahn](https://github.com/fhahn) (GitHub)
 
+#### MemorySSA
+
+Alina Sbirlea \
+asbirlea@google.com (email), [alinas](https://github.com/alinas) (GitHub)
+
 #### SandboxVectorizer
 
 Vasileios Porpodas \
@@ -456,6 +463,7 @@ Chandler Carruth (chandlerc@gmail.com, chandlerc@google.com, [chandlerc](https:/
 Peter Collingbourne (peter@pcc.me.uk, [pcc](https://github.com/pcc)) -- LTO \
 Evan Cheng (evan.cheng@apple.com) -- Parts of code generator not covered by someone else \
 Jake Ehrlich (jakehehrlich@google.com, [jakehehrlich](https://github.com/jakehehrlich)) -- llvm-objcopy and ObjCopy library \
+Hal Finkel (hfinkel@anl.gov, [hfinkel](https://github.com/hfinkel) -- AliasAnalysis \
 Renato Golin (rengolin@systemcall.eu, [rengolin](https://github.com/rengolin)) -- ARM backend \
 Venkatraman Govindaraju (venkatra@cs.wisc.edu, [vegovin](https://github.com/vegovin) -- Sparc backend \
 James Grosbach (grosbach@apple.com) -- MC layer \