libc: introduce "jehanne_" namespace

With this commit all functions declared in libc.h have been renamed
with the "jehanne_" prefix. This is done for several reason:

- it removes conflicts during symbol resolution when linking
  standard C libraries like newlib or musl
- it allows programs depending on a standard C library to directly
  link to a library depending on our non standard libc (eg libsec).

To ease transiction two files are provided:

- sys/include/lib9.h that can be included instead of <libc.h> to use
  the old names (via a simple set of macros)
- sys/src/lib/c/lib9.c that can be compiled with a program where the
  macro provided by lib9.h are too dumb (see for example rc or grep).

In the kernel port/lib.h has been modified accordingly and some of
the functions it directly provides has been renamed too (eg malloc
in qmalloc.c and print in devcons.c).

sys/src/lib/sec/port/egalloc.c

@@ -7,9 +7,9 @@ egpuballoc(void)
 {
 	EGpub *eg;
 
-	eg = mallocz(sizeof(*eg), 1);
+	eg = jehanne_mallocz(sizeof(*eg), 1);
 	if(eg == nil)
-		sysfatal("egpuballoc");
+		jehanne_sysfatal("egpuballoc");
 	return eg;
 }
 
@@ -21,7 +21,7 @@ egpubfree(EGpub *eg)
 	mpfree(eg->p);
 	mpfree(eg->alpha);
 	mpfree(eg->key);
-	free(eg);
+	jehanne_free(eg);
 }
 
 
@@ -30,9 +30,9 @@ egprivalloc(void)
 {
 	EGpriv *eg;
 
-	eg = mallocz(sizeof(*eg), 1);
+	eg = jehanne_mallocz(sizeof(*eg), 1);
 	if(eg == nil)
-		sysfatal("egprivalloc");
+		jehanne_sysfatal("egprivalloc");
 	return eg;
 }
 
@@ -45,7 +45,7 @@ egprivfree(EGpriv *eg)
 	mpfree(eg->pub.alpha);
 	mpfree(eg->pub.key);
 	mpfree(eg->secret);
-	free(eg);
+	jehanne_free(eg);
 }
 
 EGsig*
@@ -53,9 +53,9 @@ egsigalloc(void)
 {
 	EGsig *eg;
 
-	eg = mallocz(sizeof(*eg), 1);
+	eg = jehanne_mallocz(sizeof(*eg), 1);
 	if(eg == nil)
-		sysfatal("egsigalloc");
+		jehanne_sysfatal("egsigalloc");
 	return eg;
 }
 
@@ -66,5 +66,5 @@ egsigfree(EGsig *eg)
 		return;
 	mpfree(eg->r);
 	mpfree(eg->s);
-	free(eg);
+	jehanne_free(eg);
 }