Push down CPPFLAGS, CFLAGS and LDFLAGS.
Now ./configure should pick up those flags and hopefully make life a bit
easier for packagers. Notice that some flags which work fine for 'ld'
won't work with ghc, e.g. the combination "-Wl,-E" which 'gtk-config --libs'
suggests, so you'll usually want to set only -I or -L.
> ghc -Wl,-E
ghc-6.0: unrecognised flags: -Wl,-E
http://www.haskell.org/pipermail/glasgow-haskell-users/2003-June/005243.html
+SRC_HC_OPTS += @CPPFLAGS@ @CFLAGS@ -H16m -O
+EXTRA_LD_OPTS+= @LDFLAGS@
# These flags make flex 8-bit
SRC_FLEX_OPTS += -8
# These flags make flex 8-bit
SRC_FLEX_OPTS += -8