Implement alloca for x86 (grischka case_8). This implements alloca() on x86, at least for non-Windows. Unlike the grischka version, this patch handles both the bounded and non-bounded cases (when bounded, the alloca'd memory is covered), and when asked to allocate with 0 size, it returns 0 without any allocation. Modify the assembly files to adjust the amount of padding (the unused space after an allocation); this must be at least 1 for bounds-checking. It's recommended that the padding be identical for unchecked and bounded cases, because otherwise turning on bound-checking might change errors to non-errors.

tcc_g
tcc
tc2.c
doc
tc3s.c
p3.c
tc1.c
error.c
i386-gen1.c
test.out2
test.out3
web.sh
memdebug.c
bench
Makefile.uClibc
boundtest
prog.ref
test.ref
test.out
tcc-doc.html
ideas
tcctest.ref
linux.tcc
ldtest
libtcc_test
instr.S
p.c
p2.c
tcctest[1234]
test[1234].out
.gdb_history
tcc.1
tcc.pod
config.h
config.mak
config.texi
tests