RFR: 8180763: Improve inlining of Symbol::equals(char*,int) into CompactHashtable

[Claes Redestad]

Hi,

it appears that CompactHashtable suffers slightly from failure to 
completely
inline Symbol::equals, and this trivial patch to move the implementation 
into
the header helps to reduce instructions spent in Symbol::lookup when CDS is
enabled by 7.5%:

Bug: https://bugs.openjdk.java.net/browse/JDK-8180763
Webrev: http://cr.openjdk.java.net/~redestad/8180763/hotspot.00/

Thanks!

/Claes