ICU-1007 Add some comments about the Solaris 64-bit compiler fix.

X-SVN-Rev: 5561

icu4c/source/tools/gennorm/store.c

@@ -62,6 +62,14 @@ static uint16_t indexes[_NORM_INDEX_TOP]={ 0 };
 
 /* tool memory helper ------------------------------------------------------- */
 
+/* ---*** PORATABILITY WARNING! ***---
+On some 64-bit compilers the array field must be 64-bit aligned when you plan
+to access the data. You can write the data, but you may not be able
+to read the data back out. In general, custom memory management is discouraged.
+
+An alternate solution to this is to either use the standard malloc, or to specify
+that array is a union of several large basic C types.
+*/
 typedef struct UToolMemory {
     char name[64];
     uint32_t count, size, index;