libdpkg: Add new m_calloc()

lib/dpkg/dpkg.h

@@ -132,6 +132,7 @@ void cu_closefd(int argc, void **argv);
 
 void setcloexec(int fd, const char* fn);
 void *m_malloc(size_t);
+void *m_calloc(size_t);
 void *m_realloc(void*, size_t);
 char *m_strdup(const char *str);
 char *m_strndup(const char *str, size_t n);

lib/dpkg/libdpkg.Versions

@@ -47,6 +47,7 @@ LIBDPKG_PRIVATE {
 
 	# ‘Must do’ functions
 	m_malloc;
+	m_calloc;
 	m_realloc;
 	m_strdup;
 	m_asprintf;

lib/dpkg/mlib.c

@@ -57,6 +57,12 @@ void *m_malloc(size_t amount) {
   return r;
 }
 
+void *
+m_calloc(size_t size)
+{
+  return must_alloc(calloc(1, size));
+}
+
 void *m_realloc(void *r, size_t amount) {
   return must_alloc(realloc(r, amount));
 }