Fix RAM display on non-Linux hosts

[Rycieos]

A number of small bugs that worked together to make Linux RAM display correct, but MacOS and BSD off by a factor of 1024.

Fixes #787

Note that this was not caught by the tests, as the tests only check what __lp_ram_bytes() returns, not what _lp_ram() returns. Would be good to have that added @nojhan if you want to do that. Specifically the values of $lp_ram and $lp_ram_human.

[tomhoover]

I reset LP_ENABLE_RAM=1 with your proposed fix. I'm now seeing M32.00GiB in my prompt, even though my MacBook Pro has only 16GB.

[tomhoover]

More info:

Pressing return multiple times resulted in the following:

⏚ M225.17GiB [:~] 1 %
⏚ M47.56GiB [:~] 1 %
⏚ M62.39GiB [:~] 1 %
⏚ M256.98GiB [:~] 1 %
⏚ M218.29GiB [:~] 1 %
⏚ M198.43GiB [:~] 1 %
⏚ M149.60GiB [:~] 1 %
⏚ M134.96GiB [:~] 1 %
⏚ M128.87GiB [:~] 1 %
⏚ M122.40GiB [:~] 1 %
⏚ M110.14GiB [:~] 1 %
⏚ M114.84GiB [:~] 1 %
⏚ M111.43GiB [:~] 1 %
⏚ M108.31GiB [:~] 1 %

I'll be happy to run any tests you'd like.

[nojhan]

I added tests on lp_ram_* and (hopefully) fixed the MacOS mem counter. On my mac it seems to be (more or less) consistent with the activity monitor.

[Rycieos]

Looks like your fix was a step in the right direction. I found an issue with adding the two fields, which I fixed. I also fixed the test case. I added my own Mac as a test case, and fixed an issue I discovered on Cygwin.

[nojhan]

Seems good, works well on my setups.