Try each pkg-config query separatedly if returned list doesn't match query length

MinGW's pkg-config returns only one version even if queried for
multiple libraries.

Author: jasagredo

cabal-install-solver/src/Distribution/Solver/Types/PkgConfigDb.hs

@@ -70,12 +70,12 @@ readPkgConfigDb verbosity progdb = handle ioErrorHandler $ do
         (pkgVersions, _errs, exitCode) <-
                      getProgramInvocationOutputAndErrors verbosity
                        (programInvocation pkgConfig ("--modversion" : pkgNames))
-        case exitCode of
-          ExitSuccess -> (return . pkgConfigDbFromList . zip pkgNames) (lines pkgVersions)
-          -- if there's a single broken pc file the above fails, so we fall back into calling it individually
-          _ -> do
-             info verbosity ("call to pkg-config --modversion on all packages failed. Falling back to querying pkg-config individually on each package")
-             pkgConfigDbFromList . catMaybes <$> mapM (getIndividualVersion pkgConfig) pkgNames
+        if exitCode == ExitSuccess && length pkgNames == length pkgList
+          then (return . pkgConfigDbFromList . zip pkgNames) (lines pkgVersions)
+          else -- if there's a single broken pc file the above fails, so we fall back into calling it individually
+          do
+            info verbosity ("call to pkg-config --modversion on all packages failed. Falling back to querying pkg-config individually on each package")
+            pkgConfigDbFromList . catMaybes <$> mapM (getIndividualVersion pkgConfig) pkgNames
   where
     -- For when pkg-config invocation fails (possibly because of a
     -- too long command line).