base: Depend upon shlwapi on Windows

As noted in #16466, `System.Environment.getExecutablePath` depends upon
`PathFileExistsW` which is defined by `shlwapi`.

Fixes #16466.

libraries/base/base.cabal

@@ -365,7 +365,8 @@ Library
         -- mingw32: Unfortunately required because of a resource leak between
         --          mingwex and mingw32. the __math_err symbol is defined in
         --          mingw32 which is required by mingwex.
-        extra-libraries: wsock32, user32, shell32, msvcrt, mingw32, mingwex
+        -- shlwapi: provides PathFileExistsW
+        extra-libraries: wsock32, user32, shell32, msvcrt, mingw32, mingwex, shlwapi
         exposed-modules:
             GHC.IO.Encoding.CodePage.API
             GHC.IO.Encoding.CodePage.Table

libraries/base/tests/System/T16466.hs

+import System.Environment
+
+-- Make sure that getExecutablePath works on Windows. See #16466.
+main :: IO ()
+main = () <$ getExecutablePath
+

libraries/base/tests/System/all.T

@@ -7,3 +7,4 @@ test('T5930',   normal, compile_and_run, [''])
 test('system001',   when(opsys("mingw32"), skip), \
 	compile_and_run, [''])
 test('Timeout001', normal, compile_and_run, [''])
+test('T16466', normal, compile_and_run, [''])