Consistently do & alignMask, not % alignSize

Also add more unrelated tests for coverage

test/link/section-fragment/align-conflict.asm

@@ -0,0 +1,10 @@
+IF !DEF(SECOND)
+	def ATTRS equs ",ALIGN[2]"
+ELSE
+	def ATTRS equs "[$1337]"
+ENDC
+
+SECTION FRAGMENT "conflicting alignment", ROM0 {ATTRS}
+	db
+
+	PURGE ATTRS