Fix #19307: PGO builds of shared ext-intl are broken

We resolve the name mangling issue by including the right header file
inside an `extern "C"` declaration.

Closes GH-19310.

Author: cmb69

NEWS

@@ -6,6 +6,9 @@ PHP                                                                        NEWS
   . Fixed bug GH-19305 (Operands may be being released during comparison).
     (Arnaud)
 
+- Intl:
+  . Fixed bug GH-19307 (PGO builds of shared ext-intl are broken). (cmb)
+
 - Opcache:
   . Fixed bug GH-19301 (opcache build failure). (Remi)
 

ext/intl/idn/idn.cpp

@@ -20,8 +20,9 @@
 #include <config.h>
 #endif
 
-#include <php.h>
-
+extern "C" {
+#include "../php_intl.h"
+}
 #include <unicode/uidna.h>
 #include <unicode/ustring.h>