CMP0153: Add suggestion to use execute_process()

Source/cmCommands.cxx

@@ -219,9 +219,11 @@ void GetScriptingCommands(cmState* state)
   state->AddDisallowedCommand(
     "use_mangled_mesa", cmUseMangledMesaCommand, cmPolicies::CMP0030,
     "The use_mangled_mesa command should not be called; see CMP0030.");
-  state->AddDisallowedCommand(
-    "exec_program", cmExecProgramCommand, cmPolicies::CMP0153,
-    "The exec_program command should not be called; see CMP0153.");
+  state->AddDisallowedCommand("exec_program", cmExecProgramCommand,
+                              cmPolicies::CMP0153,
+                              "The exec_program command should not be called; "
+                              "see CMP0153. Use execute_process() instead.",
+                              "Use execute_process() instead.");
 
 #endif
 }

Tests/RunCMake/CMP0153/CMP0153-NEW-stderr.txt

@@ -1,3 +1,4 @@
 ^CMake Error at [^
 ]*/Tests/RunCMake/CMP0153/CMP0153-NEW\.cmake:[0-9]+ \(exec_program\):
-  The exec_program command should not be called; see CMP0153\.$
+  The exec_program command should not be called; see CMP0153\.  Use
+  execute_process\(\) instead\.$

Tests/RunCMake/CMP0153/CMP0153-WARN-stderr.txt

@@ -3,4 +3,6 @@
   Policy CMP0153 is not set: The exec_program command should not be called\.
   Run "cmake --help-policy CMP0153" for policy details\.  Use the cmake_policy
   command to set the policy and suppress this warning\.
+
+  Use execute_process\(\) instead\.
 This warning is for project developers\.  Use -Wno-dev to suppress it\.$