libc: define EWOULDBLOCK to be the same as EAGAIN
libc: define EWOULDBLOCK to be the same as EAGAIN

EWOULDBLOCK is an old error code from BSD. Not much uses it, and on basically
all modern systems it's defined to the same value as EAGAIN, which is the
System V value for the same condition.

Jira: ZEP-982
Change-Id: I5435ce55fa47f5bd2fac5d881b5b195b025f48a2
Signed-off-by: Anas Nashif <0d9952ec84ac43c159f6b7e7ed99a9080c00dd6e@intel.com>

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