Win64: Fix a pointer truncation bug in nspr.

nspr/pr/src/threads/combined/pruthr.c

Index: nspr/pr/src/threads/combined/pruthr.c
===================================================================
--- nspr/pr/src/threads/combined/pruthr.c	(revision 293124)
+++ nspr/pr/src/threads/combined/pruthr.c	(working copy)
@@ -73,13 +73,13 @@
 #ifndef HAVE_CUSTOM_USER_THREADS
     stack = PR_NEWZAP(PRThreadStack);
 #ifdef HAVE_STACK_GROWING_UP
-    stack->stackTop = (char*) ((((long)&type) >> _pr_pageShift)
+    stack->stackTop = (char*) ((((intptr_t)&type) >> _pr_pageShift)

[wtc, 2014/12/01 18:34:02]

In the NSPR upstream, I changed intptr_t to PRWord, which is a (poorly named)
NSPR type commonly used for this purpose. In Chromium it is fine to just use
intptr_t.

PRWord and intptr_t are both defined as __int64 in WIN64. Here is Visual C++
2010's definition of intptr_t:

#ifndef _INTPTR_T_DEFINED
 #define _INTPTR_T_DEFINED
 #ifdef _WIN64
typedef __int64 intptr_t;
 #else /* _WIN64 */
typedef _W64 int intptr_t;
 #endif /* _WIN64 */
#endif /* _INTPTR_T_DEFINED */

                   << _pr_pageShift);
 #else
 #if defined(SOLARIS) || defined (UNIXWARE) && defined (USR_SVR4_THREADS)
     stack->stackTop = (char*) &thread;
 #else
-    stack->stackTop = (char*) ((((long)&type + _pr_pageSize - 1)
+    stack->stackTop = (char*) ((((intptr_t)&type + _pr_pageSize - 1)
                 >> _pr_pageShift) << _pr_pageShift);
 #endif
 #endif
@@ -174,12 +174,12 @@
         ** Setup stackTop and stackBottom values.
         */
 #ifdef HAVE_STACK_GROWING_UP
-    ts->allocBase = (char*) ((((long)&ts) >> _pr_pageShift)
+    ts->allocBase = (char*) ((((intptr_t)&ts) >> _pr_pageShift)
                   << _pr_pageShift);
         ts->stackBottom = ts->allocBase + ts->stackSize;
         ts->stackTop = ts->allocBase;
 #else
-        ts->allocBase = (char*) ((((long)&ts + _pr_pageSize - 1)
+        ts->allocBase = (char*) ((((intptr_t)&ts + _pr_pageSize - 1)
                 >> _pr_pageShift) << _pr_pageShift);
         ts->stackTop    = ts->allocBase;
         ts->stackBottom = ts->allocBase - ts->stackSize;