Following #1512 

Ref: espeak-ng/espeak-ng-ios-app#34

I unfortunately have broken in-speech pauses by fixing ones that should
be constant-time.
This reverts such change and adds a compensation to SSML code.

This reverts commit 9f0b23f49e.

msan requires that we build all code with msan to avoid false positives.

msan requires that we build all code with msan to avoid false positives.

In Spanish the letter "r" in the alphabet is correctly pronounced as
"ERRe", instead of "Ere".

In Spanish the letter "r" in the alphabet is correctly pronounced as "ERRe", instead of "Ere".

this closes #1497

Also check for empty skip_marker name in SSML_MARK.

Fixes #975

Fixes #1512

There was a two bugs.
The first is SSML duration compensation was calculated wrong because
rate was not sync to internal global state.
The second causes pauses shorten when sonic compresses it, so I back
compensated it in wavegen.

Firstly, a ~ match is supposed to match even if there's nothing left.

Also, when p doesn't match, we should not return immediately, but skip
to the next group.

Fixes #1507

Fixes #1506

soft `з, с` if previous syllable is soft
add test for the new rules

Note: The latter part is untested code.