Merge branch 'bugfix/lwip_netdb_cpp_guards_v4.2' into 'release/v4.2'

lw-IP: Changed to C linkage in netdb.h for fixing bug when using mixed C/C++ code (v4.2)

See merge request espressif/esp-idf!11089

components/lwip/port/esp32/include/netdb.h

@@ -32,9 +32,17 @@
 
 #include "lwip/netdb.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+  
 #ifdef ESP_PLATFORM
 int getnameinfo(const struct sockaddr *addr, socklen_t addrlen,
                 char *host, socklen_t hostlen,
                 char *serv, socklen_t servlen, int flags);
 
 #endif
+
+#ifdef __cplusplus
+}
+#endif

tools/ci/check_public_headers.py

@@ -195,7 +195,7 @@ class PublicHeaderChecker:
         raise HeaderFailedBuildError()
 
     def preprocess_one_header(self, header, num, ignore_sdkconfig_issue=False):
-        all_compilation_flags = ["-w", "-P", "-E", "-include", header, self.main_c] + self.include_dir_flags
+        all_compilation_flags = ["-w", "-P", "-E", "-DESP_PLATFORM", "-include", header, self.main_c] + self.include_dir_flags
         if not ignore_sdkconfig_issue:
             # just strip commnets to check for CONFIG_... macros
             rc, out, err = exec_cmd([self.gcc, "-fpreprocessed", "-dD",  "-P",  "-E", header] + self.include_dir_flags)