Remove unused prefix.h

Since about the time of b2b196b the
SIMPLICITY_PREFIX has actually been unused, which explains why when
7592dd5 was merged containing an error, it
didn't cause any test failures.

So here we fix the issue by simply deleting the file.

Author: roconnor-blockstream

C/dag.c

@@ -3,7 +3,6 @@
 #include <stdbool.h>
 #include "bounded.h"
 #include "precomputed.h"
-#include "prefix.h"
 #include "rsort.h"
 #include "sha256.h"
 #include "simplicity_alloc.h"

C/elements-sources.mk

@@ -41,7 +41,6 @@ ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/frame.h
 ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/jets.h
 ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/limitations.h
 ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/precomputed.h
-ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/prefix.h
 ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/primitive.h
 ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/rsort.h
 ELEMENTS_SIMPLICITY_LIB_HEADERS_INT += %reldir%/sha256.h

C/jets-secp256k1.c

@@ -2,7 +2,6 @@
 #include "taptweak.h"
 
 #include "precomputed.h"
-#include "prefix.h"
 #include "sha256.h"
 #include "secp256k1/secp256k1_impl.h"
 

C/prefix.h

@@ -4,7 +4,6 @@
 
 #include "elementsJets.h"
 #include "../../limitations.h"
-#include "../../prefix.h"
 #include "../../primitive.h"
 #include "../../simplicity_alloc.h"
 #include "../../simplicity_assert.h"

C/primitive/elements/primitive.c

@@ -3,7 +3,6 @@
 #include <stdbool.h>
 
 #include "precomputed.h"
-#include "prefix.h"
 #include "simplicity_assert.h"
 
 /* Given a the 'kind' of a Simplicity type, return the SHA-256 hash of its associated TMR tag.