[flang] Move FIRSupport dependency to correct place (#125697)

This library is provided by flang, not MLIR, so it should not be part of
MLIR_LIBS.

Fixes an issue introduced in #120966.

(cherry picked from commit ee76bda)

Author: nikic

flang/lib/Optimizer/Analysis/CMakeLists.txt

@@ -12,12 +12,12 @@ add_flang_library(FIRAnalysis
   LINK_LIBS
   FIRBuilder
   FIRDialect
+  FIRSupport
   HLFIRDialect
 
   MLIR_LIBS
   MLIRFuncDialect
   MLIRLLVMDialect
   MLIRMathTransforms
   MLIROpenMPDialect
-  FIRSupport
 )