Merge pk_wrap into pk.c

We want public functions to resolve to the internal wrappers at compile-time.
For this we need the wrappers to be visible from where the public functions
are defined. A simple declaration is not enough if we want the compiler to be
able to inline the wrapper and eliminate function overhead.

This commit just copies verbatim the contents of pk_wrap.c into pk.c. The next
commit will clean up the result (redundant includes etc.).
diff --git a/library/Makefile b/library/Makefile
index 062846b..341888a 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -80,7 +80,7 @@
 		md4.o		md5.o				\
 		memory_buffer_alloc.o		nist_kw.o	\
 		oid.o		padlock.o	pem.o		\
-		pk.o		pk_wrap.o	pkcs12.o	\
+		pk.o		pkcs12.o			\
 		pkcs5.o		pkparse.o	pkwrite.o	\
 		platform.o	platform_util.o	poly1305.o	\
 		ripemd160.o	rsa_internal.o	rsa.o  		\