RFR: 8287400: Make BitMap range parameter names consistent

[Afshin Zafari]

On Sat, 26 Nov 2022 22:16:34 GMT, Afshin Zafari <duke at openjdk.org> wrote:

> The ranges are determined by 'start' and 'end' all over the bitMap.hpp and bitMap.cpp. All instances of other names for start and end are replaced.

Problem description:
Many BitMap operations take a range, specified via a pair of parameters. Some use the names "start" and "end", others use "beg" and "end", and the search functions use "l_index" and "r_index". It would be nice if these were consistent. "start" and "end" seem like a good choice. 

Patch:
The pair of `start`  and `end` used whenever a range to be defined/referred.

Should I keep `beg` and `end` and change the fewer instances of `start`?

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PR: https://git.openjdk.org/jdk/pull/11375