Properly check for required icu4c libraries

Besides that just checking for icuuc.lib does not necessarily imply
that the other libraries are available, doing it this way will not copy
the PDBs to the build folder, so these are not available in the debug
packages.  Furthermore, `CHECK_LIB` already adds the library to the
flags, so there is no need to do this manually.

Closes GH-17010.

Author: cmb69

ext/intl/config.w32

@@ -3,7 +3,10 @@
 ARG_ENABLE("intl", "Enable internationalization support", "no");
 
 if (PHP_INTL != "no") {
-	if (CHECK_LIB("icuuc.lib", "intl", PHP_INTL) &&
+	if (CHECK_LIB("icudt.lib", "intl", PHP_INTL) &&
+		CHECK_LIB("icuin.lib", "intl", PHP_INTL) &&
+		CHECK_LIB("icuio.lib", "intl", PHP_INTL) &&
+		CHECK_LIB("icuuc.lib", "intl", PHP_INTL) &&
 					CHECK_HEADER_ADD_INCLUDE("unicode/utf.h", "CFLAGS_INTL")) {
 		// always build as shared - zend_strtod.c/ICU type conflict
 		EXTENSION("intl", "php_intl.c intl_convert.c intl_convertcpp.cpp intl_error.c ", true,
@@ -115,16 +118,9 @@ if (PHP_INTL != "no") {
 				codepointiterator_methods.cpp ",
 				"intl");
 
-		ADD_FLAG("LIBS_INTL", "icudt.lib icuin.lib icuio.lib");
-
 		/* Compat for ICU before 58.1.*/
-		if (CHECK_LIB("icule.lib", "intl", PHP_INTL)) {
-			ADD_FLAG("LIBS_INTL", "icule.lib");
-		}
-		if (CHECK_LIB("iculx.lib", "intl", PHP_INTL)) {
-			ADD_FLAG("LIBS_INTL", "iculx.lib");
-		}
-
+		CHECK_LIB("icule.lib", "intl", PHP_INTL);
+		CHECK_LIB("iculx.lib", "intl", PHP_INTL);
 		ADD_FLAG("CFLAGS_INTL", "/EHsc /DUNISTR_FROM_CHAR_EXPLICIT=explicit /DUNISTR_FROM_STRING_EXPLICIT=explicit /DU_NO_DEFAULT_INCLUDE_UTF_HEADERS=1 /DU_HIDE_OBSOLETE_UTF_OLD_H=1");
 		AC_DEFINE("HAVE_INTL", 1, "Internationalization support enabled");
 	} else {