gdb pretty-printers: fix StringPrinterHelper for gdb 8.0

Latest gdb release "lazy_string" validates the array size:

  Traceback (most recent call last):
    File "/work/lo/master/solenv/gdb/libreoffice/util/string.py", line
29, in to_string
      return self.make_string(data, self.encoding, len)
    File "/work/lo/master/solenv/gdb/libreoffice/util/string.py", line
66, in make_string
      return data.lazy_string(encoding, length)
  gdb.error: Length is larger than array size.

rtl_uString has "sal_Unicode buffer[1];", which is a lie
as the real size is the same as "length".

Taking the address of "buffer" appears to avoid the exception.

Change-Id: I85710b1adfae584ba09c8d517e9b49b290e79d8a

solenv/gdb/libreoffice/sal.py

@@ -21,7 +21,7 @@ class RtlStringPrinter(StringPrinterHelper):
         super(RtlStringPrinter, self).__init__(typename, val, encoding)
 
     def data(self):
-        return self.val['buffer']
+        return self.val['buffer'].address
 
     def length(self):
         return self.val['length']
@@ -37,7 +37,7 @@ class StringPrinter(StringPrinterHelper):
 
     def data(self):
         assert self.val['pData']
-        return self.val['pData'].dereference()['buffer']
+        return self.val['pData'].dereference()['buffer'].address
 
     def length(self):
         assert self.val['pData']

solenv/gdb/libreoffice/util/string.py

@@ -52,15 +52,15 @@ class StringPrinterHelper(object):
         if not encoding:
             encoding = ''
 
-        if use_lazy_string:
-            return data.lazy_string(encoding, length)
-
         # we need to determine length, if not given (for sal_Unicode*)
         if length < 0:
             length = 0
             while data[length] != 0 and length <= 512: # arbitrary limit
                 length += 1
 
+        if use_lazy_string:
+            return data.lazy_string(encoding, length)
+
         # The gdb.Value.string() conversion works on array of bytes, but
         # the length we have is the length of the string. So we must
         # multiply it by width of character if the string is Unicode.