icu: Ticket #11959: pkgdata dies when compiled with lots'o'flags

See: http://bugs.icu-project.org/trac/ticket/11959

The patch avoids premature failure which results in a segfault.

Upstream-Status: Backport of r38081
Signed-off-by: Mike Crowe <mac@mcrowe.com>

Index: source/tools/toolutil/flagparser.c
===================================================================
--- source/tools/toolutil/flagparser.c	(revision 38046)
+++ source/tools/toolutil/flagparser.c	(working copy)
@@ -96,8 +96,8 @@
     uprv_free(buffer);
 
     T_FileStream_close(f);
-    
-    if (U_FAILURE(*status)) {
+
+    if (U_FAILURE(*status) && *status != U_BUFFER_OVERFLOW_ERROR) {
         return -1;
     }