Do not "escape" newline if comment ends with ESC character.

Fixes: 127521510
Test: manual
Change-Id: I88a8eb2ca94b8aa06e2682d2c14f9e74f5ada286

androidmk/cmd/androidmk/androidmk_test.go

@@ -1062,6 +1062,17 @@ include test/vts/tools/build/Android.host_config.mk
 vts_config {
 	name: "vtsconf",
 }
+`,
+	},
+	{
+		desc: "comment with ESC",
+		in: `
+# Comment line 1 \
+# Comment line 2
+`,
+		expected: `
+// Comment line 1 \
+// Comment line 2
 `,
 	},
 }

androidmk/parser/parser.go

@@ -485,10 +485,12 @@ loop:
 		case '\\':
 			p.parseEscape()
 			if p.tok == '\n' {
-				comment += "\n"
-			} else {
-				comment += "\\" + p.scanner.TokenText()
+				// Special case: '\' does not "escape" newline in comment (b/127521510)
+				comment += "\\"
+				p.accept(p.tok)
+				break loop
 			}
+			comment += "\\" + p.scanner.TokenText()
 			p.accept(p.tok)
 		case '\n':
 			p.accept('\n')