ICU: fix build with clang-5

pkgs/os-specific/darwin/apple-source-releases/ICU/clang-5.patch

···
+diff --git a/icuSources/i18n/ucoleitr.cpp b/icuSources/i18n/ucoleitr.cpp
+index ecc94c9..936452f 100644
+--- a/icuSources/i18n/ucoleitr.cpp
++++ b/icuSources/i18n/ucoleitr.cpp
+@@ -320,7 +320,7 @@ ucol_nextProcessed(UCollationElements *elems,
+                    int32_t            *ixHigh,
+                    UErrorCode         *status)
+ {
+-    return (UCollationPCE::UCollationPCE(elems)).nextProcessed(ixLow, ixHigh, status);
++    return (UCollationPCE(elems)).nextProcessed(ixLow, ixHigh, status);
+ }
+ 
+ 
+@@ -384,7 +384,7 @@ ucol_previousProcessed(UCollationElements *elems,
+                    int32_t            *ixHigh,
+                    UErrorCode         *status)
+ {
+-    return (UCollationPCE::UCollationPCE(elems)).previousProcessed(ixLow, ixHigh, status);
++    return (UCollationPCE(elems)).previousProcessed(ixLow, ixHigh, status);
+ }
+ 
+ U_NAMESPACE_BEGIN

pkgs/os-specific/darwin/apple-source-releases/ICU/default.nix

···
 appleDerivation {
   nativeBuildInputs = [ cctools ];
 
+  patches = [ ./clang-5.patch ];
+
   postPatch = ''
     substituteInPlace makefile \
       --replace /usr/bin/ "" \