RWMutex/Semaphore Redux

[aleksclark]

Ok, I apologize if this is bad form, I'm pretty new to the Java/Kotlin ecosystem. I've tried to take @btwilk 's work and update it to conform to the latest version of kotlinx.coroutines in support of issue #94 However, I haven't been able to get it to compile due to a problem with the compileKotlinJS task:

> Task :kotlinx-coroutines-core:compileKotlinJs FAILED
e: /home/aleks/data/work/kotlinx.coroutines/kotlinx-coroutines-core/common/src/sync/ReadWriteMutex.kt: (13, 18): JavaScript name (ReadWriteMutex) generated for this declaration clashes with another declaration: fun ReadWriteMutex(): ReadWriteMutex
e: /home/aleks/data/work/kotlinx.coroutines/kotlinx-coroutines-core/common/src/sync/ReadWriteMutex.kt: (22, 1): JavaScript name (ReadWriteMutex) generated for this declaration clashes with another declaration: interface ReadWriteMutex
e: /home/aleks/data/work/kotlinx.coroutines/kotlinx-coroutines-core/common/src/sync/ReadWriteMutex.kt: (40, 33): Unresolved reference: describeAddLast
e: /home/aleks/data/work/kotlinx.coroutines/kotlinx-coroutines-core/common/src/sync/Semaphore.kt: (42, 33): Unresolved reference: describeAddLast

I don't know what the deal is, as the api looks the same as Mutex. Any help here appreciated :)

[qwwdfsad]

I am closing this PR, see #94 (comment)