JBRE 8u sources cannot be build on Ubuntu 8.10 (gcc 8.2.0)

Fixed compiler errors in hotspot sources

src/os/linux/vm/os_linux.inline.hpp

@@ -116,6 +116,11 @@ inline int os::ftruncate(int fd, jlong length) {
 
 inline struct dirent* os::readdir(DIR* dirp, dirent *dbuf)
 {
+// readdir_r has been deprecated since glibc 2.24.
+// See https://sourceware.org/bugzilla/show_bug.cgi?id=19056 for more details.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
   dirent* p;
   int status;
   assert(dirp != NULL, "just checking");
@@ -129,6 +134,8 @@ inline struct dirent* os::readdir(DIR* dirp, dirent *dbuf)
     return NULL;
   } else
     return p;
+
+#pragma GCC diagnostic pop  
 }
 
 inline int os::closedir(DIR *dirp) {

src/os_cpu/linux_x86/vm/os_linux_x86.cpp

@@ -541,6 +541,7 @@ JVM_handle_linux_signal(int sig,
   err.report_and_die();
 
   ShouldNotReachHere();
+  return false;
 }
 
 void os::Linux::init_thread_fpu_state(void) {