- a few more uninitialized variables
- make variables local to a single file static
- replace use of WT_UNUSED_RET with error checking of the call (the
macro was using a GCC extension clang doesn't like)
With these changes, clang is mostly silent using the following options:
-Weverything
-Wno-cast-align
-Wno-conversion
-Wno-covered-switch-default
-Wno-documentation-unknown-command
-Wno-format-nonliteral
-Wno-language-extension-token
-Wno-missing-noreturn
-Wno-packed
-Wno-padded
-Wno-switch-enum
-Wno-zero-length-array
Also, minor KNF whitespace cleanups.