BString: add support for move semantics with C++11 and up.

This implements the "rule of 5" for this type. While the copy operation for
BString was already using shallow copies of the underlying data, this change
further optimizes moving the data from one object to another.

While it is not the intention to implement move semantics to all types in the
legacy Haiku/Be kits, data types like BString are good candidates, because move
operations are often useful when working with data within an application.

In this implementation, the internal data of the string object will be set to
NULL, thus leaving an empty string.

Change-Id: I16bf9424f9b17f622b0b57659b80628e18760288
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4428
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

support/String: Revert 6c67c7d63 to fix double-free

6c67c7d63 was attempting to fix a leak caught by a static analysis
tool, but it actually just introduced a double-free bug. Running
`UnitTester BString` will result in a crash.

The original code was correct because, in the event that realloc()
fails in BString::_Resize(), the value of fPrivateData is still
retained. It will be freed by the destructor of BString only if
fPrivateData is not shared by another BString instance, since BStrings
are copy-on-write.

Note that while the change in 6c67c7d63 caused tests to fail, that
doesn't mean those tests are ideal. They only trigger
BString::_Resize() to fail because they depend on implementation
details of hoard2 which limits allocations via malloc() to
1GB. Most malloc() implementations will allow allocations of arbitrary
sizes using anonymous mappings (mmap on Linux, or create_area() in
Haiku). This is a much bigger change, so for now I'm just adding some
comments so that we can revisit these tests if we make a change to the
allocator.

Change-Id: I208c1c7a76b6b4409d237b911c62bb3198e49dab
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2060
Reviewed-by: Stephan Aßmus <superstippi@gmx.de>

Support kit: Fixed issues in BString unit tests

1: Changed CPPUNIT_ASSERT -> CPPUNIT_ASSERT_EQUAL
2: Fixed coding style: Added two lines after including libraries, maintained 80 characters(MAX) in each line and space at comment start
3: Fixed the failure for "BString::Search" test "i != 0 by chaning the testing method(StartsWith->IStartsWith) and changed the string to be searched(sT->st)

Change-Id: I1237d1f2d0e3af7757963cc940bae929f487f088

* Fixed warning.
* Automatic whitespace cleanup.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@39632 a95241bf-73f2-0310-859d-f6bbb57e9c96

* fixed Adopt(BString, len) test, as after adopt the source string should
be empty, thus the pointer into that string should point to empty data...



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24104 a95241bf-73f2-0310-859d-f6bbb57e9c96

address compiler warnings


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@10125 a95241bf-73f2-0310-859d-f6bbb57e9c96

Another patch from Oliver Tappe: BString behaves better when the user supplies out-of bounds values in Insert(), Remove(), etc.
Code is refactored, and it fully complies with our guidelines.
Tests have been updated too (hint: try the replace tests with R5 and our implementation...)


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5348 a95241bf-73f2-0310-859d-f6bbb57e9c96

Added some comments to the tests


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1521 a95241bf-73f2-0310-859d-f6bbb57e9c96

More tests for BString


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1352 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Fixed warning.
* Automatic whitespace cleanup.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@39632 a95241bf-73f2-0310-859d-f6bbb57e9c96

* fixed Adopt(BString, len) test, as after adopt the source string should
be empty, thus the pointer into that string should point to empty data...



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24104 a95241bf-73f2-0310-859d-f6bbb57e9c96

address compiler warnings


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@10125 a95241bf-73f2-0310-859d-f6bbb57e9c96

Another patch from Oliver Tappe: BString behaves better when the user supplies out-of bounds values in Insert(), Remove(), etc.
Code is refactored, and it fully complies with our guidelines.
Tests have been updated too (hint: try the replace tests with R5 and our implementation...)


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5348 a95241bf-73f2-0310-859d-f6bbb57e9c96

Added some comments to the tests


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1521 a95241bf-73f2-0310-859d-f6bbb57e9c96

More tests for BString


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@1352 a95241bf-73f2-0310-859d-f6bbb57e9c96