use CC variable to compile strtold.c

- strtold is compiled w/o optimizations
Fixes Issue 7656, Fixes Issue 7715. Escape special characters in ddoc
d code.
fix Issue 8408 - Purity calculation should be improved
fix split usage in d_do_test.d

As mentioned in https://github.com/D-Programming-Language/phobos/pull/934#issuecomment-10282813

The *correct* behavior for `splitter(string, string)` is to create empty tokens when input is empty (or when there are trailing separators or whatnot).

My fix was creating a problem here, where a new empty token was being (correctly) generated:
http://d.puremagic.com/test-results/pull.ghtml?runid=368596&logid=7

`../src/dmd -m32 -Icompilable   -odtest_results/compilable -oftest_results/compilable/99bottles_0.o -c compilable/99bottles.d compilable/`

Anyways, the simple fix is to just use the simple string-dedicated `split(string)`, which does not produce empty tokens.
Fix calling of std.string.format
Make deprecations as warnings the default

Since wanting to have deprecations as warnings is probably what most
people wants, make it the default. Also rename -di to -dw and introduce
-de to get the old default behaviour of having deprecations as errors.
-d stays untouched for backwards compatibility and those crazy people
that doesn't even want to know about deprecated features.
fix Issue 9035 - Nested struct `init` is lvalue and can be modified
fix Issue 9036 - postblit is called for nested structs when assigning `init`
Revert "revert D2 pull #972" to re-merge #972

This reverts commit 7c370f71641c4408ddc9ebd5709e6e182e34ad2b.
fix VS2008 build
add REQUIRED_ARGS to d_do_test
add some documentation
fix test: same implementation of dtime() for Win32 and Win64
fix Issue 9070 - nothrow of constructer/destructor isn't correct
fix win64 alignment of data segment
fix Issue 9069 - struct literals are treated as lvalues
fix tests for win64
Merge pull request #1316 from rainers/fix_test_dhry

fix test dhry for Win64
Merge pull request #1318 from rainers/win64_fix_dataseg_alignment

fix win64 alignment of data segment
Merge pull request #1314 from rainers/improve_d_do_test

add REQUIRED_ARGS to d_do_test