cmake support: first cut from David Vaz work.i

cmake/CheckPrototypeExists.cmake

@@ -0,0 +1,39 @@
+# AWI, downloaded from KDE repository since has not yet been transferred
+# to cmake repository as of 2006-07-31.
+# http://websvn.kde.org/trunk/KDE/kdelibs/cmake/modules/CheckPrototypeExists.cmake?rev=505849&view=markup
+#
+# - Check if the prototype for a function exists.
+# CHECK_PROTOTYPE_EXISTS (FUNCTION HEADER VARIABLE)
+#
+#  FUNCTION - the name of the function you are looking for
+#  HEADER - the header(s) where the prototype should be declared
+#  VARIABLE - variable to store the result
+#
+
+# AWI further change from C++ to C since that is the core PLplot language.
+INCLUDE(CheckCSourceCompiles)
+
+MACRO(CHECK_PROTOTYPE_EXISTS _SYMBOL _HEADER _RESULT)
+   SET(_INCLUDE_FILES)
+   FOREACH(it ${_HEADER})
+      SET(_INCLUDE_FILES "${_INCLUDE_FILES}#include <${it}>\n")
+   ENDFOREACH(it)
+
+   SET(_CHECK_PROTO_EXISTS_SOURCE_CODE "
+${_INCLUDE_FILES}
+void cmakeRequireSymbol(int dummy,...){(void)dummy;}
+int main()
+{
+#ifndef ${_SYMBOL}
+#ifndef _MSC_VER
+  cmakeRequireSymbol(0,&${_SYMBOL});
+#else
+  char i = sizeof(&${_SYMBOL});
+#endif
+#endif
+  return 0;
+}
+")
+   CHECK_C_SOURCE_COMPILES("${_CHECK_PROTO_EXISTS_SOURCE_CODE}" ${_RESULT})
+ENDMACRO(CHECK_PROTOTYPE_EXISTS _SYMBOL _HEADER _RESULT)
+