[8] RFR (S) 8033251: Use DWARF debug symbols for Linux 32-bit as default

[Tim Bell]

Buck:

> May I please get a review of this simple backport to replace stabs with
> DWARF for 32-bit Linux builds. This is needed as newer toolchains no
> longer support stabs.
>
> bug report:
> https://bugs.openjdk.java.net/browse/JDK-8033251
>
> JDK 9 changeset:
> http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/2750fb4ad9ac
>
> JDK 8 webrev for review:
> http://cr.openjdk.java.net/~dbuck/8033251.0/

Looks good.  Your changes are in line with what JDK 9 did, only a bit 
more specific to the ARCH that is building.

In JDK 9 I see a check for $(FASTDEBUG_CFLAGS/$(BUILDARCH) but setting:
    FASTDEBUG_CFLAGS += -g

In JDK 8 you check $(FASTDEBUG_CFLAGS/$(BUILDARCH)) and set:
    FASTDEBUG_CFLAGS/$(BUILDARCH) = -g

and the same for $(OPT_CFLAGS/$(BUILDARCH)

Tim