ELF parser: fix off-by-one error

I don't know why Arvid subtracted 1 when he wrote this code. But it was
wrong. Fortunately, the section size was not used afterwards, but the next
commit will.

Change-Id: I117816bf0f5e469b8d34fffd153dc8383b00b94a
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/corelib/plugin/qelfparser_p.cpp

@@ -224,7 +224,7 @@ int QElfParser::parse(const char *dataStart, ulong fdlen, const QString &library
                 return Corrupt;
             }
             *pos = sh.offset;
-            *sectionlen = sh.size - 1;
+            *sectionlen = sh.size;
             if (shnam[1] == 'q')
                 return QtMetaDataSection;
         }