Replace http://man7.org links with https://man7.org links.

I suspect the way http:// dies is that browsers just interpret it as
https:// anyway, but there's no reason not to just bulk fix all these at
source.

Change-Id: I38fa91728846d7c33207ef1bdadd4910eac9e941
diff --git a/libc/bionic/spawn.cpp b/libc/bionic/spawn.cpp
index 38f99ad..8cee8b8 100644
--- a/libc/bionic/spawn.cpp
+++ b/libc/bionic/spawn.cpp
@@ -186,7 +186,7 @@
                        char* const argv[],
                        char* const env[],
                        int exec_fn(const char* path, char* const argv[], char* const env[])) {
-  // See http://man7.org/linux/man-pages/man3/posix_spawn.3.html
+  // See https://man7.org/linux/man-pages/man3/posix_spawn.3.html
   // and http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_spawn.html
 
   ScopedSignalBlocker ssb;