Enable -Wcpp-undef

e5b3492f tried (again) to enable -Wcpp-undef in mk/warnings.mk,

SRC_HC_OPTS_STAGE1 += $(WERROR) #-Wcpp-undef
SRC_HC_OPTS_STAGE2 += $(WERROR) #-Wcpp-undef

Unfortunately, this caused build failures in boot libraries on some platforms (e.g. time on Darwin). Resolve these and reenable -Wcpp-undef.

An alternative would be to instead only add -Wcpp-undef to GhcRtsHcOpts, GhcStage1HcOpts and GhcStage2HcOpts.

Trac metadata

Trac field	Value
Version	8.1
Type	Task
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 5

added Ttask Trac import labels

changed milestone to %8.4.1

Trac metadata

Trac field	Value
Version	8.1 → 8.3

mentioned in commit 6267d8c9

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Pnormal label