Apply ICU patches for ICU tickets 6175 (ISO-2022 and ...

third_party/icu38/uconv.security.header.patch

+--- r22777/source/common/unicode/ucnv.h 2007-08-31 12:39:14.294200000 -0700
++++ chrome.canonical/source/common/unicode/ucnv.h       2009-03-23 12:30:09.850131000 -0700
+@@ -870,6 +870,8 @@
+ typedef enum UConverterUnicodeSet {
+     /** Select the set of roundtrippable Unicode code points. @stable ICU 2.6 */
+     UCNV_ROUNDTRIP_SET,
++    /** Select the set of Unicode code points with roundtrip or fallback mappings. @draft ICU 4.0 */
++    UCNV_ROUNDTRIP_AND_FALLBACK_SET,
+     /** Number of UConverterUnicodeSet selectors. @stable ICU 2.6 */
+     UCNV_SET_COUNT
+ } UConverterUnicodeSet;
+@@ -878,11 +880,16 @@
+ /**
+  * Returns the set of Unicode code points that can be converted by an ICU converter.
+  *
+- * The current implementation returns only one kind of set (UCNV_ROUNDTRIP_SET):
++ * Returns one of several kinds of set:
++ *
++ * 1. UCNV_ROUNDTRIP_SET
++ *
+  * The set of all Unicode code points that can be roundtrip-converted
+- * (converted without any data loss) with the converter.
++ * (converted without any data loss) with the converter (ucnv_fromUnicode()).
+  * This set will not include code points that have fallback mappings
+  * or are only the result of reverse fallback mappings.
++ * This set will also not include PUA code points with fallbacks, although
++ * ucnv_fromUnicode() will always uses those mappings despite ucnv_setFallback().
+  * See UTR #22 "Character Mapping Markup Language"
+  * at http://www.unicode.org/reports/tr22/
+  *
+@@ -893,6 +900,12 @@
+  *   by comparing its roundtrip set with the set of ExemplarCharacters from
+  *   ICU's locale data or other sources
+  *
++ * 2. UCNV_ROUNDTRIP_AND_FALLBACK_SET
++ *
++ * The set of all Unicode code points that can be converted with the converter (ucnv_fromUnicode())
++ * when fallbacks are turned on (see ucnv_setFallback()).
++ * This set includes all code points with roundtrips and fallbacks (but not reverse fallbacks).
++ *
+  * In the future, there may be more UConverterUnicodeSet choices to select
+  * sets with different properties.
+  *