On a clean tree, I get:

cc -DHAVE_CONFIG_H -I. -I/Users/dda/wt/git/wt-qqqq-global-ref/test/packing -I../.. -I../../api/leveldb -I../.. -I../../../src/include -I../../../test/utility -DCLANG_ANALYZER -Qunused-arguments -I/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home//include -I/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home//include/darwin -I/Users/dda/wt/snappy/installed/snappy-1.1.1/include -I/Users/dda/wt/ext/lz4/installed/include -std=c11 -Wall -Wextra -Waddress -Waggregate-return -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat -Winline -Wmissing-declarations -Wmissing-field-initializers -Wnested-externs -Wpointer-arith -Wredundant-decls -Wshadow -Wunused -Wwrite-strings -Werror=sign-conversion -Wno-shift-negative-value -Wunreachable-code -Werror -g -Wall -DCLANG_ANALYZER -MT intpack-test.o -MD -MP -MF $depbase.Tpo -c -o intpack-test.o ../../../test/packing/intpack-test.c &&\
mv -f $depbase.Tpo $depbase.Po
/bin/sh /Users/dda/wt/git/wt-qqqq-global-ref/libtool --tag=CC --mode=link cc -std=c11 -Wall -Wextra -Waddress -Waggregate-return -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat -Winline -Wmissing-declarations -Wmissing-field-initializers -Wnested-externs -Wpointer-arith -Wredundant-decls -Wshadow -Wunused -Wwrite-strings -Werror=sign-conversion -Wno-shift-negative-value -Wunreachable-code -Werror -g -Wall -DCLANG_ANALYZER -static -o intpack-test intpack-test.o ../../test/utility/libtest_util.la ../../libwiredtiger.la -ldl -lpthread -lz -llz4 -lsnappy
libtool: link: cc -std=c11 -Wall -Wextra -Waddress -Waggregate-return -Wbad-function-cast -Wdeclaration-after-statement -Wformat-security -Wformat -Winline -Wmissing-declarations -Wmissing-field-initializers -Wnested-externs -Wpointer-arith -Wredundant-decls -Wshadow -Wunused -Wwrite-strings -Werror=sign-conversion -Wno-shift-negative-value -Wunreachable-code -Werror -g -Wall -DCLANG_ANALYZER -o intpack-test intpack-test.o /Users/dda/wt/git/wt-qqqq-global-ref/test/utility/.libs/libtest_util.a -L/Users/dda/wt/snappy/installed/snappy-1.1.1/lib -L/Users/dda/wt/ext/lz4/installed/lib ../../.libs/libwiredtiger.a -ldl -lpthread -lz -llz4 /Users/dda/wt/snappy/installed/snappy-1.1.1/lib/libsnappy.dylib
Undefined symbols for architecture x86_64:
"___wt_process", referenced from:
___wt_clock_to_nsec in libwiredtiger.a(time.o)
(maybe you meant: ___wt_process_id)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [intpack-test] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all] Error 2
make: *** [makeall] Error 2

I have recently upgraded my tool set on OS/X. I suspect that this has to do with a difference in how different linkers work with regard to references to data items.