Prune the .may_include files a bit; detect unused lines in them

src/common/.may_include

@@ -3,9 +3,6 @@ common/*.h
 lib/*/*.h
 
 # XXXX These all belong somewhere else
-ht.h
-linux_syscalls.inc
 siphash.h
 src/ext/timeouts/timeout.c
 tor_queue.h
-tor_readpassphrase.h

src/lib/crypt_ops/.may_include

@@ -9,7 +9,6 @@ lib/encoding/*.h
 lib/fs/*.h
 lib/lock/*.h
 lib/malloc/*.h
-lib/err/*.h
 lib/intmath/*.h
 lib/sandbox/*.h
 lib/string/*.h

src/lib/process/.may_include

@@ -4,6 +4,7 @@ lib/cc/*.h
 lib/container/*.h
 lib/ctime/*.h
 lib/err/*.h
+lib/intmath/*.h
 lib/fs/*.h
 lib/log/*.h
 lib/malloc/*.h

src/lib/tls/.may_include

@@ -1,16 +1,16 @@
 orconfig.h
+
 lib/arch/*.h
 lib/cc/*.h
-lib/ctime/*.h
 lib/container/*.h
 lib/crypt_ops/*.h
-lib/intmath/*.h
+lib/ctime/*.h
 lib/encoding/*.h
-lib/err/*.h
+lib/intmath/*.h
+lib/log/*.h
 lib/net/*.h
 lib/string/*.h
 lib/testsupport/testsupport.h
 lib/tls/*.h
-lib/log/*.h
 
 ciphers.inc