Move some error flags to warnings

Appears to be a GCC bug causing `restrict` warnings, and some
`maybe-uninitialized` ones that are more senstive.  Downgrade them to
warnings since getting the compiler upgraded is time-sensitive.

Signed-off-by: Samuel E. Browne <[email protected]>

Author: sebrowne

cmake/ProjectCompilerPostConfig.cmake

@@ -65,10 +65,12 @@ set(upcoming_warnings
     array-bounds=2
     class-memaccess
     dangling-pointer=2
+    maybe-uninitialized
     mismatched-new-delete
     overloaded-virtual=1
     pessimizing-move
     range-loop-construct
+    restrict
     unused-but-set-variable
     uninitialized
     ${Trilinos_ADDITIONAL_WARNINGS}
@@ -112,7 +114,6 @@ set(promoted_warnings
     int-to-pointer-cast
     logical-not-parentheses
     main
-    maybe-uninitialized
     memset-elt-size
     memset-transposed-args
     misleading-indentation
@@ -127,7 +128,6 @@ set(promoted_warnings
     parentheses
     pointer-sign
     reorder
-    restrict
     return-type
     self-move
     sequence-point