build: Fix stp-asan path in QEMU configure flags.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build: Add missing dependency of klee-asan on llvm.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build: Always run ASAN-enabled KLEE targets, same as normal KLEE targets.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build: Ignore errors from clean target commands.

This ensures that the clean targets continue running even if some
commands fail, ensuring that as much as possible is actually cleaned.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build: Extract S2E source path from Makefile location.

Hardcoding the path name is not flexible enough.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
build/guest: Merge rules for building shared libraries.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
gitignore: Ignore all init_env .so versions.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
gitignore: Prefix entries for non-global patterns with /.

While the entries being prefixed are unlikely to clash with newly-created
files, it is good style to use full paths for specific ignore patterns.

Signed-off-by: Diego Biurrun <diego@biurrun.de>