REORG: include: move THREAD_LOCAL and __decl_thread() to compiler.h

Since these are used as type attributes or conditional clauses, they
are used about everywhere and should not require a dependency on
thread.h. Moving them to compiler.h along with other similar statements
like ALIGN() etc looks more logical; this way they become part of the
base API. This allowed to remove thread-t.h from ~12 files, one was
found to only require thread-t and not thread and dict.c was found to
require thread.h.
diff --git a/src/dict.c b/src/dict.c
index 50fe1eb..903f073 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -3,6 +3,7 @@
 #include <import/eb32tree.h>
 #include <import/ebistree.h>
 #include <haproxy/dict.h>
+#include <haproxy/thread.h>
 
 struct dict *new_dict(const char *name)
 {