diff -rauN jdk-jdk-9.0.4+12/src/java.base/unix/native/libjava/childproc.c jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.base/unix/native/libjava/childproc.c
--- jdk-jdk-9.0.4+12/src/java.base/unix/native/libjava/childproc.c	2018-01-13 03:07:38.000000000 +0100
+++ jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.base/unix/native/libjava/childproc.c	2021-05-16 14:34:22.286800941 +0200
@@ -33,6 +33,7 @@
 
 #include "childproc.h"
 
+const char * const *parentPathv;
 
 ssize_t
 restartableWrite(int fd, const void *buf, size_t count)
diff -rauN jdk-jdk-9.0.4+12/src/java.base/unix/native/libjava/childproc.h jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.base/unix/native/libjava/childproc.h
--- jdk-jdk-9.0.4+12/src/java.base/unix/native/libjava/childproc.h	2018-01-13 03:07:38.000000000 +0100
+++ jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.base/unix/native/libjava/childproc.h	2021-05-16 14:34:53.816831584 +0200
@@ -118,7 +118,7 @@
  * The cached and split version of the JDK's effective PATH.
  * (We don't support putenv("PATH=...") in native code)
  */
-const char * const *parentPathv;
+extern const char * const *parentPathv;
 
 ssize_t restartableWrite(int fd, const void *buf, size_t count);
 int restartableDup2(int fd_from, int fd_to);
diff -rauN jdk-jdk-9.0.4+12/src/java.security.jgss/unix/native/libj2gss/NativeFunc.c jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.security.jgss/unix/native/libj2gss/NativeFunc.c
--- jdk-jdk-9.0.4+12/src/java.security.jgss/unix/native/libj2gss/NativeFunc.c	2018-01-13 03:07:38.000000000 +0100
+++ jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.security.jgss/unix/native/libj2gss/NativeFunc.c	2021-05-16 14:49:58.261235281 +0200
@@ -28,6 +28,9 @@
 #include <dlfcn.h>
 #include "NativeFunc.h"
 
+/* global GSS function table */
+GSS_FUNCTION_TABLE_PTR ftab;
+
 /* standard GSS method names (ordering is from mapfile) */
 static const char RELEASE_NAME[]                = "gss_release_name";
 static const char IMPORT_NAME[]                 = "gss_import_name";
diff -rauN jdk-jdk-9.0.4+12/src/java.security.jgss/unix/native/libj2gss/NativeFunc.h jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.security.jgss/unix/native/libj2gss/NativeFunc.h
--- jdk-jdk-9.0.4+12/src/java.security.jgss/unix/native/libj2gss/NativeFunc.h	2018-01-13 03:07:38.000000000 +0100
+++ jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/java.security.jgss/unix/native/libj2gss/NativeFunc.h	2021-05-16 14:50:08.671248326 +0200
@@ -265,6 +265,6 @@
 typedef GSS_FUNCTION_TABLE *GSS_FUNCTION_TABLE_PTR;
 
 /* global GSS function table */
-GSS_FUNCTION_TABLE_PTR ftab;
+extern GSS_FUNCTION_TABLE_PTR ftab;
 
 #endif
diff -rauN jdk-jdk-9.0.4+12/src/jdk.sctp/unix/native/libsctp/Sctp.h jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/jdk.sctp/unix/native/libsctp/Sctp.h
--- jdk-jdk-9.0.4+12/src/jdk.sctp/unix/native/libsctp/Sctp.h	2018-01-13 03:07:38.000000000 +0100
+++ jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/jdk.sctp/unix/native/libsctp/Sctp.h	2021-05-16 15:40:57.905491930 +0200
@@ -322,12 +322,12 @@
 
 #endif /* __linux__ */
 
-sctp_getladdrs_func* nio_sctp_getladdrs;
-sctp_freeladdrs_func* nio_sctp_freeladdrs;
-sctp_getpaddrs_func* nio_sctp_getpaddrs;
-sctp_freepaddrs_func* nio_sctp_freepaddrs;
-sctp_bindx_func* nio_sctp_bindx;
-sctp_peeloff_func* nio_sctp_peeloff;
+extern sctp_getladdrs_func* nio_sctp_getladdrs;
+extern sctp_freeladdrs_func* nio_sctp_freeladdrs;
+extern sctp_getpaddrs_func* nio_sctp_getpaddrs;
+extern sctp_freepaddrs_func* nio_sctp_freepaddrs;
+extern sctp_bindx_func* nio_sctp_bindx;
+extern sctp_peeloff_func* nio_sctp_peeloff;
 
 jboolean loadSocketExtensionFuncs(JNIEnv* env);
 
diff -rauN jdk-jdk-9.0.4+12/src/jdk.sctp/unix/native/libsctp/SctpNet.c jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/jdk.sctp/unix/native/libsctp/SctpNet.c
--- jdk-jdk-9.0.4+12/src/jdk.sctp/unix/native/libsctp/SctpNet.c	2018-01-13 03:07:38.000000000 +0100
+++ jdk-jdk-9.0.4+12-gcc10-default-no-fcommon-patch/src/jdk.sctp/unix/native/libsctp/SctpNet.c	2021-05-16 15:42:27.565614895 +0200
@@ -28,6 +28,14 @@
 #include <dlfcn.h>
 
 #include "Sctp.h"
+
+sctp_getladdrs_func* nio_sctp_getladdrs;
+sctp_freeladdrs_func* nio_sctp_freeladdrs;
+sctp_getpaddrs_func* nio_sctp_getpaddrs;
+sctp_freepaddrs_func* nio_sctp_freepaddrs;
+sctp_bindx_func* nio_sctp_bindx;
+sctp_peeloff_func* nio_sctp_peeloff;
+
 #include "jni.h"
 #include "jni_util.h"
 #include "nio_util.h"