Remove -D_FORTIFY_SOURCE=2 because it only works with -O.  Upstream
disables -O because (they claim) it leads to miscompilation.

Remove -Wstrict-aliasing=0.  If these warnings happen, they are
serious.

Remove -Wredundant-decls.  This happens several times, and is not
serious.

Remove -m32/-m64 flags. The buildsystem is native and thus correct and -m32 doesn't work on s390.

diff -up acpica-unix-20120913/generate/unix/Makefile.config.opts acpica-unix-20120913/generate/unix/Makefile.config
--- acpica-unix-20120913/generate/unix/Makefile.config.opts	2012-09-13 21:37:42.000000000 +0200
+++ acpica-unix-20120913/generate/unix/Makefile.config	2012-11-23 12:23:01.000000000 +0100
@@ -104,14 +104,10 @@ ACPICA_HEADERS = \
 # automatically included in -Wall.
 #
 CFLAGS += \
-    $(BITSFLAG) \
     -D$(HOST) \
     -D_GNU_SOURCE \
-    -D_FORTIFY_SOURCE=2 \
     -I$(ACPICA_INCLUDE)
 
-LDFLAGS += $(BITSFLAG)
-
 CWARNINGFLAGS = \
     -ansi \
     -Wall \
@@ -121,7 +117,6 @@ CWARNINGFLAGS = \
     -Wformat=2 \
     -Wmissing-declarations \
     -Wmissing-prototypes \
-    -Wstrict-aliasing=0 \
     -Wstrict-prototypes \
     -Wswitch-default \
     -Wpointer-arith \
@@ -142,7 +137,7 @@ CWARNINGFLAGS += \
     -Wnested-externs \
     -Wold-style-declaration \
     -Wold-style-definition \
-    -Wredundant-decls \
+    -Wno-redundant-decls \
     -Wtype-limits
 
 #