Add regression test for multiple coverage goal instances

Covered goals is a set of unique elements

Author: peterschrammel

regression/cbmc-cover/branch-loop1/main.c

@@ -0,0 +1,11 @@
+int main(int argc, char **argv)
+{
+  for(int i = 0; i < 4; i++)
+  {
+    char c;
+    __CPROVER_input("c", c);
+    if(c == 42)
+      return 0;
+  }
+  return 1;
+}

regression/cbmc-cover/branch-loop1/test.desc

@@ -0,0 +1,11 @@
+CORE
+main.c
+--xml-ui --cover branch
+activate-multi-line-match
+EXIT=0
+SIGNAL=0
+</inputs>\n\s*<goal id="main\.coverage\.1"/>\n\s*<goal id="main\.coverage\.2"/>\n\s*<goal id="main\.coverage\.3"/>\n\s*<goal id="main\.coverage\.5"/>\n\s*</test>
+--
+^warning: ignoring
+--
+Expect each goal only occur once per test.