Handles if a space is encountered while parsing the rule

kati and GNU make may have blank lines in the middle of commands declared in rules.
Add compatibility for this.

Change-Id: Iae03053c0cb901074c26420c0c6ac1c0e00d99de

androidmk/parser/parser.go

@@ -413,6 +413,9 @@ loop:
 				p.accept('\t')
 				newLine = false
 				continue loop
+			} else if p.tok == '\n' {
+				p.accept('\n')
+				continue loop
 			} else if p.parseDirective() {
 				newLine = false
 				continue

androidmk/parser/parser_test.go

@@ -84,6 +84,22 @@ endif`,
 			},
 		},
 	},
+	{
+		name: "Blank line in rule's command",
+		in:   `all:
+	echo first line
+
+	echo second line`,
+		out: []Node{
+			&Rule{
+				Target: SimpleMakeString("all", NoPos),
+				RecipePos: NoPos,
+				Recipe: "echo first line\necho second line",
+				Prerequisites: SimpleMakeString("", NoPos),
+			},
+		},
+	},
+
 }
 
 func TestParse(t *testing.T) {