add performbuild flag for dynamic executables

Stackage/CompleteBuild.hs

@@ -206,6 +206,7 @@ getPerformBuild buildFlags Settings {..} = PerformBuild
     , pbEnableTests = bfEnableTests buildFlags
     , pbEnableHaddock = bfEnableHaddock buildFlags
     , pbEnableLibProfiling = bfEnableLibProfile buildFlags
+    , pbEnableExecDyn = bfEnableExecDyn buildFlags
     , pbVerbose = bfVerbose buildFlags
     , pbAllowNewer = bfSkipCheck buildFlags
     }

Stackage/InstallBuild.hs

@@ -51,6 +51,7 @@ getPerformBuild plan InstallFlags{..} =
     , pbEnableTests        = ifEnableTests
     , pbEnableHaddock      = ifEnableHaddock
     , pbEnableLibProfiling = ifEnableLibProfiling
+    , pbEnableExecDyn      = ifEnableExecDyn
     , pbVerbose            = ifVerbose
     , pbAllowNewer         = ifSkipCheck
     }

Stackage/PerformBuild.hs

@@ -64,6 +64,7 @@ data PerformBuild = PerformBuild
     , pbEnableTests        :: Bool
     , pbEnableHaddock      :: Bool
     , pbEnableLibProfiling :: Bool
+    , pbEnableExecDyn      :: Bool
     , pbVerbose            :: Bool
     , pbAllowNewer         :: Bool
     -- ^ Pass --allow-newer to cabal configure
@@ -317,6 +318,7 @@ singleBuild pb@PerformBuild {..} SingleBuild {..} =
         tell' $ "--flags=" ++ flags
         when (pbEnableLibProfiling && pcEnableLibProfile) $
             tell' "--enable-library-profiling"
+        when pbEnableExecDyn $ tell' "--enable-executable-dynamic"
       where
         tell' x = tell (x:)