add test for #5243

testsuite/tests/ghc-regress/parser/should_compile/T5243.hs

+   { import T5243A; main = print bar }

testsuite/tests/ghc-regress/parser/should_compile/T5243.stderr

+[1 of 2] Compiling T5243A           ( T5243A.hs, T5243A.o )
+[2 of 2] Compiling Main             ( T5243.hs, T5243.o )
+Linking T5243 ...

testsuite/tests/ghc-regress/parser/should_compile/T5243A.hs

+module T5243A where
+bar = True

testsuite/tests/ghc-regress/parser/should_compile/all.T

@@ -90,3 +90,5 @@ test('NondecreasingIndentation', normal, compile, [''])
 test('mc15', normal, compile, [''])
 test('mc16', normal, compile, [''])
 test('EmptyDecls', normal, compile, [''])
+
+test('T5243', normal, multimod_compile, ['T5243',''])