rename the digest provider files to avoid any name clashes with other folders

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9083)

providers/common/digests/build.info

@@ -1,5 +1,5 @@
 SOURCE[../../../libcrypto]=\
-        sha2.c sha3.c
+        sha2_prov.c sha3_prov.c
 
 SOURCE[../../fips]=\
-        sha2.c sha3.c
+        sha2_prov.c sha3_prov.c

providers/default/digests/build.info

@@ -1,17 +1,17 @@
 SOURCE[../../../libcrypto]=\
-        null.c
+        null_prov.c
 
 IF[{- !$disabled{blake2} -}]
   SOURCE[../../../libcrypto]=\
-          blake2.c blake2b.c blake2s.c
+          blake2_prov.c blake2b_prov.c blake2s_prov.c
 ENDIF
 
 IF[{- !$disabled{sm3} -}]
   SOURCE[../../../libcrypto]=\
-          sm3.c
+          sm3_prov.c
 ENDIF
 
 IF[{- !$disabled{md5} -}]
   SOURCE[../../../libcrypto]=\
-          md5.c md5_sha1.c
+          md5_prov.c md5_sha1_prov.c
 ENDIF

providers/legacy/digests/build.info

@@ -1,24 +1,24 @@
 IF[{- !$disabled{md2} -}]
   SOURCE[../../legacy]=\
-          md2.c
+          md2_prov.c
 ENDIF
 
 IF[{- !$disabled{md4} -}]
   SOURCE[../../legacy]=\
-          md4.c
+          md4_prov.c
 ENDIF
 
 IF[{- !$disabled{mdc2} -}]
   SOURCE[../../legacy]=\
-          mdc2.c
+          mdc2_prov.c
 ENDIF
 
 IF[{- !$disabled{whirlpool} -}]
   SOURCE[../../legacy]=\
-          wp.c
+          wp_prov.c
 ENDIF
 
 IF[{- !$disabled{rmd160} -}]
   SOURCE[../../legacy]=\
-          ripemd.c
+          ripemd_prov.c
 ENDIF