Add -Wconditional-uninitialized to clang strict warnings.

Reviewed-by: Rich Salz <rsalz@openssl.org>

Configure

diff --git a/Configure b/Configure
index cfd1980..fb20e85 100755
--- a/Configure
+++ b/Configure
@@ -101,13 +101,13 @@
 
 # These are used in addition to $gcc_devteam_warn when the compiler is clang.
 # TODO(openssl-team): fix problems and investigate if (at least) the
-# following warnings can also be enabled: -Wconditional-uninitialized,
+# following warnings can also be enabled:
 # -Wswitch-enum, -Wunused-macros, -Wmissing-field-initializers,
 # -Wmissing-variable-declarations,
 # -Wincompatible-pointer-types-discards-qualifiers, -Wcast-align,
 # -Wunreachable-code -Wunused-parameter -Wlanguage-extension-token
 # -Wextended-offsetof
-my $clang_devteam_warn = "-Wno-unused-parameter -Wno-missing-field-initializers -Wno-language-extension-token -Wno-extended-offsetof -Qunused-arguments";
+my $clang_devteam_warn = "-Wno-unused-parameter -Wno-missing-field-initializers -Wno-language-extension-token -Wno-extended-offsetof -Wconditional-uninitialized -Qunused-arguments";
 
 my $strict_warnings = 0;