Fix build issues in tgt-pcb

On Ubunto 10.10 (32 bit) tgt-pcb would not build because there were
include file issues. This patch fixes those and uses the C++ include
version where appropriate.

tgt-pcb/pcb.cc

@@ -24,7 +24,9 @@
 # include "version_base.h"
 # include "version_tag.h"
 # include "pcb_config.h"
-# include  <string.h>
+# include  <cassert>
+# include  <cstdio>
+# include  <cstring>
 # include  "pcb_priv.h"
 # include  "ivl_target.h"
 

tgt-pcb/pcb_priv.h

@@ -23,7 +23,7 @@
 # include  <set>
 # include  <list>
 # include  <map>
-# include  <ivl_target.h>
+# include  "ivl_target.h"
 
 extern int scan_scope(ivl_scope_t scope);
 

tgt-pcb/scope.cc

@@ -21,6 +21,7 @@
 # include <map>
 # include <string>
 # include <cassert>
+# include <cstdio>
 
 using namespace std;
 

tgt-pcb/show_netlist.cc

@@ -18,6 +18,7 @@
  */
 
 # include  "pcb_priv.h"
+# include  <cassert>
 # include  <cstdio>
 
 using namespace std;

tgt-pcb/show_pcb.cc

@@ -19,6 +19,8 @@
 
 # include  "pcb_config.h"
 # include  "pcb_priv.h"
+# include  <cassert>
+# include  <cstdio>
 
 using namespace std;