[DynInst_API:] nasm/yasm deprecated on Linux

[Stan Cox <scox@xxxxxxxxxx>]

Yep, we still do builds on 386 for Fedora.  I came across a couple of 
minor issues for the 386 build.
I notice the 386 testsuite build looks for nasm, which is used by 
test6LS-x86.asm.  The test uses 32 bit register names; but I didn't see 
any 386 specifics in it.  It should be straightforward to convert the 
test to use gas and have it work on 386 and x8664.  I just did the 
minimum and commented it out.
+# nasm/yasm are deprecated
+#  if("${DYNINST_PLATFORM}" MATCHES "i386")
+#    enable_language(ASM_NASM)
+#  endif()

Also related to 386 is the Fedora 34 builds now default to -flto (link 
time optimizer).  For x86_64, aarch64, ppcle64 the dyninst builds worked 
fine (have not tested the result) but the build failed on 386 (out of 
memory).  I just turned on -fno-lto for 386 only; that should be good 
enough.