Tweaked the error message and updated the tests accordingly

Author: eugeneepshteyn

flang/lib/Semantics/check-omp-structure.cpp

@@ -1156,8 +1156,7 @@ void OmpStructureChecker::CheckThreadprivateOrDeclareTargetVar(
                         (sym->has<MainProgramDetails>() ||
                             sym->has<ModuleDetails>())) {
                       context_.Say(name->source,
-                          "The module name or main program name cannot be in a "
-                          "%s "
+                          "The module name cannot be in a %s "
                           "directive"_err_en_US,
                           ContextDirectiveAsFortran());
                     } else if (!IsSaved(*name->symbol) &&

flang/test/Semantics/OpenMP/declare-target03.f90

@@ -13,7 +13,7 @@ subroutine bar
 program main
   use mod1
 
-  !ERROR: The module name or main program name cannot be in a DECLARE TARGET directive
+  !ERROR: The module name cannot be in a DECLARE TARGET directive
   !$omp declare target (mod1)
 
   ! This is now allowed: "main" is implicitly declared symbol separate

flang/test/Semantics/OpenMP/threadprivate03.f90

@@ -10,7 +10,7 @@ program main
   use mod1
   integer, parameter :: i = 1
 
-  !ERROR: The module name or main program name cannot be in a THREADPRIVATE directive
+  !ERROR: The module name cannot be in a THREADPRIVATE directive
   !$omp threadprivate(mod1)
 
   ! This is now allowed, since "main" is implicitly declared symbol,