ZAM fix for inlining empty function bodies as the sole elements of an if-else

testing/btest/Baseline/opt.null-inline-branch/output

@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+got through the conditional

testing/btest/opt/null-inline-branch.zeek

@@ -0,0 +1,19 @@
+# @TEST-DOC: Regression test for past ZAM issues with inlining empty functions in conditionals
+#
+# @TEST-EXEC: zeek -b -O ZAM %INPUT >output
+# @TEST-EXEC: btest-diff output
+
+function empty_func() {}
+
+# Use a global to avoid constant propagation optimizing out the conditional.
+global bar = F;
+
+event zeek_init()
+	{
+	if ( bar )
+		empty_func();
+	else
+		empty_func();
+
+	print "got through the conditional";
+	}