Add test cases for unreachable heap memory from globals

tests/regression/76-memleak/08-unreachable-mem.c

@@ -0,0 +1,12 @@
+//PARAM: --set ana.malloc.unique_address_count 1 --set ana.activated[+] memLeak
+#include <stdlib.h>
+
+int *g;
+
+int main(int argc, char const *argv[]) {
+    g = malloc(sizeof(int));
+    // Reference to g's heap contents is lost here
+    g = NULL;
+
+    return 0; //WARN
+}

tests/regression/76-memleak/09-unreachable-with-local-var.c

@@ -0,0 +1,17 @@
+//PARAM: --set ana.malloc.unique_address_count 1 --set ana.activated[+] memLeak
+#include <stdlib.h>
+
+int *g;
+
+int main(int argc, char const *argv[]) {
+    g = malloc(sizeof(int));
+    // Reference to g's heap contents is lost here
+    g = NULL;
+    // We get a false positive for p's memory being unreachable
+    // It's still leaked, but due to free() being commented out
+    // TODO: Should we only improve the error reporting for unreachable memory in this case?
+    int *p = malloc(sizeof(int));
+    //free(p);
+
+    return 0; //WARN
+}