Issue #1756 - Clean up ICU patch.

We don't need ICU_UNUM_HAS_FORMATDOUBLEFORFIELDS because we don't support any
ICU other than the one in-tree.

intl/icu-patches/unum_formatDoubleForFields.diff

@@ -23,7 +23,7 @@ diff --git a/intl/icu/source/i18n/unicode/unum.h b/intl/icu/source/i18n/unicode/
   * <h2> Number Format C API </h2>
   *
   * Number Format C API  Provides functions for
-@@ -647,16 +648,67 @@ U_STABLE int32_t U_EXPORT2
+@@ -647,16 +648,66 @@ U_STABLE int32_t U_EXPORT2
  unum_formatUFormattable(const UNumberFormat* fmt,
                          const UFormattable *number,
                          UChar *result,
@@ -71,16 +71,15 @@ diff --git a/intl/icu/source/i18n/unicode/unum.h b/intl/icu/source/i18n/unicode/
 +* @see unum_parseDouble
 +* @see UFieldPositionIterator
 +* @see UNumberFormatFields
-+* @draft ICU 59
++* @stable ICU 59
 +*/
-+U_DRAFT int32_t U_EXPORT2
++U_STABLE int32_t U_EXPORT2
 +unum_formatDoubleForFields(const UNumberFormat* format,
 +                           double number,
 +                           UChar* result,
 +                           int32_t resultLength,
 +                           UFieldPositionIterator* fpositer,
 +                           UErrorCode* status);
-+#define ICU_UNUM_HAS_FORMATDOUBLEFORFIELDS
 +
 +/**
  * Parse a string into an integer using a UNumberFormat.