stubs: do not expose internals

Remove the export decoration on implementations.  The details are indirected
through a pointer to the data.  There is no need to make the data itself
visible.  This was detected during work to support Windows/MSVCRT.

Author: compnerd

stdlib/public/stubs/UnicodeExtendedGraphemeClusters.cpp.gyb

@@ -58,7 +58,6 @@ trie_generator.serialize(grapheme_cluster_break_property_table)
 
 #include <stdint.h>
 
-SWIFT_RUNTIME_STDLIB_INTERFACE
 const uint8_t _swift_stdlib_GraphemeClusterBreakPropertyTrieImpl[] = {
 % for byte in trie_generator.trie_bytes:
   ${byte},
@@ -124,7 +123,6 @@ extended_grapheme_cluster_rules_matrix = \
 }%
 
 
-SWIFT_RUNTIME_STDLIB_INTERFACE
 const uint16_t _swift_stdlib_ExtendedGraphemeClusterNoBoundaryRulesMatrixImpl[] = {
 % for row in get_extended_grapheme_cluster_rules_matrix(grapheme_cluster_break_property_table):
   ${row},