Avoid `container` namespace clash with gcc-11's libstdc++ headers.

https://bugs.gentoo.org/786264
--- a/src/nnet/xmltempl.cc
+++ b/src/nnet/xmltempl.cc
@@ -22,10 +22,10 @@ CXml * x ::print () const { \
 #define RP(x) x
 
 #define child(x,tag) retval->AddChild (*xml_print (x,tag));
-#define container(x,tag) retval->AddChild (*xml_print_container (x,tag));
+#define epos_container(x,tag) retval->AddChild (*xml_print_container (x,tag));
 #define child_opt(x,tag) if(x) child(x,tag)
 #define child_enum(x,tag,enumS) retval->AddChild (*xml_print (enumS[x],tag));
-#define container_opt(x,tag) if(x.size()) container(x,tag)
+#define container_opt(x,tag) if(x.size()) epos_container(x,tag)
 #define structure(x,tag) retval->AddChild (*xml_print_str (x,tag));
 #define structure_opt(x,tag,write_cond) if (write_cond) structure(x,tag)
 
@@ -40,7 +40,7 @@ CXml * x ::print () const { \
 #define CHILD(x)		child(x,#x)
 #define CHILD_OPT(x)		child_opt(x,#x)
 #define CHILD_ENUM(x,enumS)	child_enum(x,#x,enumS)
-#define CONTAINER(x)		container(x,#x)
+#define CONTAINER(x)		epos_container(x,#x)
 #define CONTAINER_OPT(x)	container_opt (x,#x)
 #define STRUCTURE(x)		structure(x,#x)
 #define STRUCTURE_OPT(x,cond)	structure_opt(x,#x,cond)
@@ -60,7 +60,7 @@ return retval; }
 #undef child
 #undef child_opt
 #undef child_enum
-#undef container
+#undef epos_container
 #undef container_opt
 #undef structure
 #undef structure_opt
@@ -82,7 +82,7 @@ CString x ::read (CRox *xml) { \
 #define child(x,tag) err += xml_read (xml,x,tag);
 #define child_opt(x,tag) err += xml_read(xml,x,tag,false);
 #define child_enum(x,tag,enumS) err += xml_read_enum(xml,x,enumS,tag);
-#define container(x,tag) err += xml_read_container (xml,x,tag);
+#define epos_container(x,tag) err += xml_read_container (xml,x,tag);
 #define container_opt(x,tag) err += xml_read_container (xml,x,tag,false);
 #define structure(x,tag) err += xml_read_str (xml,x,tag);
 #define structure_opt(x,tag,write_cond) err += xml_read_str (xml,x,tag,false);
@@ -105,7 +105,7 @@ else return ""; }
 #undef child
 #undef child_opt
 #undef child_enum
-#undef container
+#undef epos_container
 #undef container_opt
 #undef structure
 #undef structure_opt
@@ -119,7 +119,7 @@ else return ""; }
 
 #define XMLIZE(x,tag) x tmp##tag; retval->AddChild (*tmp##tag.printTemplate ());
 #define child(x,tag) 
-#define container(x,tag) 
+#define epos_container(x,tag) 
 #define child_opt(x,tag) 
 #define child_enum(x,tag,enumS) 
 #define container_opt(x,tag) 
@@ -145,7 +145,7 @@ CRox *xmltempl ()
 #undef child
 #undef child_opt
 #undef child_enum
-#undef container
+#undef epos_container
 #undef container_opt
 #undef structure
 #undef structure_opt
@@ -171,7 +171,7 @@ CXml * x ::printTemplate () const { \
 	CXml *retval = new CXml (#tag,1,0,"comment","structure " #x); \
 	retval->SetFF(DODELETE);
 #define child(x,tag) retval->AddChild (*(new CXml(tag,1,0,"comment",#x))->SetFF(DODELETE));
-#define container(x,tag) 
+#define epos_container(x,tag) 
 #define child_opt(x,tag) 
 #define child_enum(x,tag,enumS) 
 #define container_opt(x,tag)