ape: move strdup() from libbsd to libap (from sources)

including <string.h> should be enougth to make strdup()
available.

sys/include/ape/bsd.h

@@ -34,10 +34,8 @@ extern int	ffs(unsigned int);
 extern void	bhappy(void*);
 extern int	rresvport(int*);
 extern int	rcmd(char**, int, char*, char*, char*, int*);
-extern char*	strdup(char*);
 extern int	strcasecmp(char*, char*);
 extern int	strncasecmp(char*, char*,int);
-extern void* memccpy(void*, void*, int, size_t);
 
 extern int	getopt(int, char**, char*);
 extern int	opterr;

sys/include/ape/string.h

@@ -9,6 +9,7 @@ extern "C" {
 #endif
 
 extern void *memcpy(void *, const void *, size_t);
+extern void *memccpy(void*, void*, int, size_t);
 extern void *memmove(void *, const void *, size_t);
 extern char *strcpy(char *, const char *);
 extern char *strncpy(char *, const char *, size_t);
@@ -17,6 +18,7 @@ extern char *strncat(char *, const char *, size_t);
 extern int memcmp(const void *, const void *, size_t);
 extern int strcmp(const char *, const char *);
 extern int strcoll(const char *, const char *);
+extern char *strdup(char*);
 extern int strncmp(const char *, const char *, size_t);
 extern size_t strxfrm(char *, const char *, size_t);
 extern void *memchr(const void *, int, size_t);

sys/src/ape/lib/ap/gen/mkfile

@@ -55,6 +55,7 @@ ALLOFILES=\
 	strtoull.$O\
 	strxfrm.$O\
 	toupper.$O\
+	strdup.$O\
 
 # cull things in the per-machine directories from this list
 OFILES=	`{rc ./reduce $O $objtype $ALLOFILES}

sys/src/ape/lib/bsd/mkfile

@@ -49,7 +49,6 @@ OFILES=\
 	strncasecmp.$O\
 	socket.$O\
 	socketpair.$O\
-	strdup.$O\
 	pty.$O\
 	writev.$O\