Properly handle embedded nul delimited string lists

For example:

reserved-names="res1\0res2\0res3";

Where \0 is an actual embedded NUL in the source instead of a string
escape. To achieve this, use the len given by the lexer instead of
strlen.

Without this patch dtc will mangle the output and possibly hang on
realloc.

data.c

@@ -74,7 +74,7 @@ struct data data_copy_escape_string(const char *s, int len)
 	struct data d;
 	char *q;
 
-	d = data_grow_for(empty_data, strlen(s)+1);
+	d = data_grow_for(empty_data, len + 1);
 
 	q = d.val;
 	while (i < len) {

tests/embedded_nul_equiv.dts

@@ -0,0 +1,6 @@
+/dts-v1/;
+
+/ {
+	reserved-names = "aaaaaaaaaaaaaaaaaa\0bbbbbb\0ccccccccccccc";
+	reserved-ranges = < 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0  >;
+};

tests/run_tests.sh

@@ -275,6 +275,10 @@ libfdt_tests () {
     run_dtc_test -I dts -O dtb -o sourceoutput.test.dtb sourceoutput.dts
     run_dtc_test -I dts -O dtb -o sourceoutput.test.dts.test.dtb sourceoutput.test.dts
     run_test dtbs_equal_ordered sourceoutput.test.dtb sourceoutput.test.dts.test.dtb
+
+    run_dtc_test -I dts -O dtb -o embedded_nul.test.dtb embedded_nul.dts
+    run_dtc_test -I dts -O dtb -o embedded_nul_equiv.test.dtb embedded_nul_equiv.dts
+    run_test dtbs_equal_ordered embedded_nul.test.dtb embedded_nul_equiv.test.dtb
 }
 
 dtc_tests () {