Bignum: extract bignum_mod.h functions

Extract functions declared in bignum_mod.h into a source file with a
matching name.

We are doing this because:

- This is a general best practice/convention
- We hope that this will make resolving merge conflicts in the future
  easier
- Having them in a unified source file is a premature optimisation at
  this point

This makes library/bignum_new.c empty and therefore it is deleted.

Signed-off-by: Janos Follath <janos.follath@arm.com>

include/mbedtls/mbedtls_config.h

@@ -2010,9 +2010,9 @@
  * Enable the multi-precision integer library.
  *
  * Module:  library/bignum.c
- *          library/bignum_new.c
  *          library/bignum_core.c
  *          library/bignum_mod_raw.c
+ *          library/bignum_mod.c
  * Caller:  library/dhm.c
  *          library/ecp.c
  *          library/ecdsa.c

library/CMakeLists.txt

@@ -18,9 +18,9 @@ set(src_crypto
     asn1write.c
     base64.c
     bignum.c
-    bignum_new.c
     bignum_core.c
     bignum_mod_raw.c
+    bignum_mod.c
     camellia.c
     ccm.c
     chacha20.c

library/Makefile

@@ -83,9 +83,9 @@ OBJS_CRYPTO= \
 	     asn1write.o \
 	     base64.o \
 	     bignum.o \
-	     bignum_new.o \
 	     bignum_core.o \
 	     bignum_mod_raw.o \
+	     bignum_mod.o \
 	     camellia.o \
 	     ccm.o \
 	     chacha20.o \

library/bignum_mod.c

@@ -26,10 +26,6 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
 #include "mbedtls/bignum.h"
-#include "bignum_core.h"
-#include "bignum_mod.h"
-#include "bignum_mod_raw.h"
-#include "constant_time_internal.h"
 
 #if defined(MBEDTLS_PLATFORM_C)
 #include "mbedtls/platform.h"
@@ -41,6 +37,11 @@
 #define mbedtls_free        free
 #endif
 
+#include "bignum_core.h"
+#include "bignum_mod.h"
+#include "bignum_mod_raw.h"
+#include "constant_time_internal.h"
+
 int mbedtls_mpi_mod_residue_setup( mbedtls_mpi_mod_residue *r,
                                    mbedtls_mpi_mod_modulus *m,
                                    mbedtls_mpi_uint *p,