Makefile updates:

Turn on optimization
Remove some redundancy in FLAGS

etc/mk/minix.sys.mk

@@ -100,8 +100,7 @@ PIE_AFLAGS?=	    -fPIC -DPIC
 
 # Helpers for cross-compiling
 HOST_CC?=	cc
-#XXX: Temporarily disable -O for MINIX
-#HOST_CFLAGS?=	-O
+HOST_CFLAGS?=	-O
 HOST_CFLAGS?=
 HOST_COMPILE.c?=${HOST_CC} ${HOST_CFLAGS} ${HOST_CPPFLAGS} -c
 HOST_COMPILE.cc?=      ${HOST_CXX} ${HOST_CXXFLAGS} ${HOST_CPPFLAGS} -c
@@ -112,8 +111,7 @@ HOST_LINK.c?=	${HOST_CC} ${HOST_CFLAGS} ${HOST_CPPFLAGS} ${HOST_LDFLAGS}
 .endif
 
 HOST_CXX?=	c++
-#XXX: Temporarily disable -O for MINIX
-#HOST_CXXFLAGS?=	-O
+HOST_CXXFLAGS?=	-O
 HOST_CXXFLAGS?=
 
 HOST_CPP?=	cpp

etc/mk/sys.mk

@@ -42,8 +42,7 @@ DBG?=	-O1 -fgcse -fstrength-reduce -fgcse-after-reload
 # see src/doc/HACKS for details
 DBG?=	-O1
 .else
-#XXX: Temporarily disable -O for MINIX
-#DBG?=	-O
+DBG?=	-O
 DBG?=
 .endif
 CFLAGS?=	${DBG}