Add issue code for if-generate in PSL vunits (ghdl/ghdl#1372)

issues/issue_1372.vhd

@@ -0,0 +1,46 @@
+vunit issue_vunit (issue(psl)) {
+
+  -- All is sensitive to rising edge of clk
+  default clock is rising_edge(clk);
+
+  -- GHDL crash if condition evaluates to true
+  test_g : if true generate
+
+    -- This assertion holds
+    CHECK_0_a : assert always (a -> b);
+
+  end generate test_g;
+
+}
+
+
+library ieee;
+  use ieee.std_logic_1164.all;
+  use ieee.numeric_std.all;
+
+
+entity issue is
+  port (
+    clk : in std_logic
+  );
+end entity issue;
+
+
+architecture psl of issue is
+
+  component sequencer is
+    generic (
+      seq : string
+    );
+    port (
+      clk  : in  std_logic;
+      data : out std_logic
+    );
+  end component sequencer;
+
+  signal a, b : std_logic := '1';
+
+begin
+
+
+end architecture psl;