Compatibility: allow ports to customize semaphore / mutex creation This commit adds new port methods: `#newSemaphore` and `#newMutex`. This allows ports to return customized objects. This is needed to accomodate different implementations / behaviors of semaphores among dialects (e.g, Pharo)

Initialize UDIS86-based disassembler lazily

Compatiblity: do not access Exeption's `parameter` instvar directly ...but through an accessor. (At least) Pharo has no instvar `parameter`.

Pharo port: add new make target `source` This commit makes new target - `source` which only generates sources for Pharo. This is to be used from other (Pharo) projects using LibGDBs (e.g., Tinyrossa).

Pharo port: fix makefile This commit fixes an error when running Pharo's `make` in fresh clone caused by multiple attempts to clone smalltalk `makefiles`.

Add Pharo version of `GDBPortlib` ...that uses LibUnix from pharo-hacks [1]. Also, add dependency on `LibCompat` [1]: https://github.com/janvrany/pharo-hacks

Add PTerm as prerequisite of LibGDBs on Pharo

Add utility method `GDBDebugger >> #cli:` ...as a shorthand for opening a CLI for interactive debugging.

Compatiblity: refactor `GDBPTY` to allow separate stream objects for reading and writing This commit changes `GDBPTY` to keep read- and write- streams of both PTY's master and slave as separate objects. This enhances portability as some dialects do not support (character) read-write streams, e.g., Pharo.

Introduce `GDBPortlib` to facilitate porting to other dialects This commit introduces `GDBPortlib` in order to allow port to other Smalltalk dialects, e.g, Pharo. Dialect specific code should go there. For now, this includes creation of pipes and PTYs and spawning processes. Since now we use `GDBPortlib`s to encapsulate dialect-specific code, (what used to be) `GDBStXSimpleProcess` and `GDBStXUnixProcess` are no longer Smalltalk/X specific. Therefore they have been renamed to `GDBSimpleProcess` and `GDBUnixProcess`