Rename library/ecp_alt.h to ecp_internal_alt.h

library/ecp_alt.h (declaring individual functions of the ECP module that can
be substituted, included when building the library with
MBEDTLS_ECP_INTERNAL_ALT enabled) clashes with ecp_alt.h (not provided,
declaring types of the ECP module when the whole implementation is
substituted, included when building the library with MBEDTLS_ECP_ALT enabled).
Depending on the search path during build, this can make MBEDTLS_ECP_ALT
unusable.

Rename library/ecp_alt.h to follow the naming convention of other alt headers:
MBEDTLS_XXX_ALT corresponds to xxx_alt.h.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/ecp.c

@@ -99,7 +99,7 @@
 #define mbedtls_free       free
 #endif
 
-#include "ecp_alt.h"
+#include "ecp_internal_alt.h"
 
 #if !defined(MBEDTLS_ECP_NO_INTERNAL_RNG)
 #if defined(MBEDTLS_HMAC_DRBG_C)

library/ecp_internal_alt.h

@@ -1,5 +1,5 @@
 /**
- * \file ecp_alt.h
+ * \file ecp_internal_alt.h
  *
  * \brief Function declarations for alternative implementation of elliptic curve
  * point arithmetic.
@@ -293,5 +293,5 @@ int mbedtls_internal_ecp_normalize_mxz( const mbedtls_ecp_group *grp,
 
 #endif /* MBEDTLS_ECP_INTERNAL_ALT */
 
-#endif /* ecp_alt.h */
+#endif /* ecp_internal_alt.h */