Bug 1853619 - Build double-conversion for icupkg on big endians. r=sergesanspaille

Differential Revision: https://phabricator.services.mozilla.com/D188775

config/external/icu/i18n/moz.build

@@ -22,3 +22,13 @@ if CONFIG["TARGET_ENDIANNESS"] == "big":
     HOST_DEFINES["U_I18N_IMPLEMENTATION"] = True
     HOST_SOURCES += sources
     HOST_SOURCES += other_sources
+    HOST_SOURCES += [
+        "/mfbt/double-conversion/double-conversion/bignum-dtoa.cc",
+        "/mfbt/double-conversion/double-conversion/bignum.cc",
+        "/mfbt/double-conversion/double-conversion/cached-powers.cc",
+        "/mfbt/double-conversion/double-conversion/double-to-string.cc",
+        "/mfbt/double-conversion/double-conversion/fast-dtoa.cc",
+        "/mfbt/double-conversion/double-conversion/fixed-dtoa.cc",
+        "/mfbt/double-conversion/double-conversion/string-to-double.cc",
+        "/mfbt/double-conversion/double-conversion/strtod.cc",
+    ]