convert linalg library from Fortran to C++

lib/linalg/lsame.cpp

@@ -0,0 +1,17 @@
+
+#include <cctype>
+
+extern "C" {
+
+#include "lmp_f2c.h"
+
+logical lsame_(const char *a, const char *b)
+{
+  char ua, ub;
+  if (!a || !b) return FALSE_;
+
+  ua = toupper(*a);
+  ub = toupper(*b);
+  return (ua == ub) ? TRUE_ : FALSE_;
+}
+}