Add the missing test files.

src/testdir/test_signs.in

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+Tests for signs
+STARTTEST
+:so small.vim
+:if !has("signs")
+:  e! test.ok
+:  wq! test.out
+:endif
+:"
+:sign define JumpSign text=x
+:exe 'sign place 42 line=2 name=JumpSign buffer=' . bufnr('')
+:" Split the window to the bottom to verify :sign-jump will stay in the current
+:" window if the buffer is displayed there
+:bot split
+:exe 'sign jump 42 buffer=' . bufnr('')
+:call append(line('$'), winnr())
+:$-1,$w! test.out
+ENDTEST
+
+STARTTEST
+:qa!
+ENDTEST
+

src/testdir/test_signs.ok

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+
+2