Change cabal new-build to unconditionally build all packages.

This changes the behavior to NOT look at the current working
directory to decide what to build.  Instead it always goes
and builds everything, if you don't specify any arguments.

Requested by @cocreature.

Please discuss!

I haven't adjusted the tests in integration-tests2 yet.

Signed-off-by: Edward Z. Yang <[email protected]>

In this variation, being inside a package directory results in only that package being built.

Signed-off-by: Edward Z. Yang <[email protected]>

Author: ezyang

cabal-install/Distribution/Client/TargetSelector.hs

@@ -447,7 +447,7 @@ resolveTargetSelectors [] [] [] =
     ([TargetSelectorNoTargetsInProject], [])
 
 resolveTargetSelectors [] _opinfo [] =
-    ([TargetSelectorNoTargetsInCwd], [])
+    ([], [TargetAllPackages Nothing])
 
 resolveTargetSelectors ppinfo _opinfo [] =
     ([], [TargetPackage TargetImplicitCwd (head ppinfo) Nothing])