[crac] RFR: Fix compilation with clang

[Jan Kratochvil]

../../src/hotspot/os/linux/crac_linux.cpp:192:13: error: using the result of an assignment as a condition without parentheses [-Werror,-Wparentheses]
  while (dp = readdir(dir)) {
         ~~~^~~~~~~~~~~~~~
../../src/hotspot/os/linux/crac_linux.cpp:192:13: note: place parentheses around the assignment to silence this warning
  while (dp = readdir(dir)) {
            ^
         (                )
../../src/hotspot/os/linux/crac_linux.cpp:192:13: note: use '==' to turn this assignment into an equality comparison
  while (dp = readdir(dir)) {
            ^
            ==
../../src/hotspot/os/linux/crac_linux.cpp:402:13: error: using the result of an assignment as a condition without parentheses [-Werror,-Wparentheses]
  while (dp = readdir(dir)) {
         ~~~^~~~~~~~~~~~~~
../../src/hotspot/os/linux/crac_linux.cpp:402:13: note: place parentheses around the assignment to silence this warning
  while (dp = readdir(dir)) {
            ^
         (                )
../../src/hotspot/os/linux/crac_linux.cpp:402:13: note: use '==' to turn this assignment into an equality comparison
  while (dp = readdir(dir)) {
            ^
            ==
2 errors generated.

-------------

Commit messages:
 - Fix compilation with clang

Changes: https://git.openjdk.org/crac/pull/122/files
 Webrev: https://webrevs.openjdk.org/?repo=crac&pr=122&range=00
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/crac/pull/122.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/122/head:pull/122

PR: https://git.openjdk.org/crac/pull/122