[Driver] [NetBSD] Add -D_REENTRANT when using sanitizers

NetBSD intends to support only reentrant interfaces in interceptors.
When -lpthread is used without _REENTRANT defined, things are
not guaranteed to work.

This is especially important for <stdio.h> and sanitization of
interfaces around FILE.  Some APIs have alternative modes depending
on the _REENTRANT definition, and NetBSD intends to support sanitization
of the _REENTRANT ones.

Differential Revision: https://reviews.llvm.org/D55654

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@349650 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Driver/ToolChains/NetBSD.cpp

@@ -457,3 +457,11 @@ SanitizerMask NetBSD::getSupportedSanitizers() const {
   }
   return Res;
 }
+
+void NetBSD::addClangTargetOptions(const ArgList &,
+                                   ArgStringList &CC1Args,
+                                   Action::OffloadKind) const {
+  const SanitizerArgs &SanArgs = getSanitizerArgs();
+  if (SanArgs.hasAnySanitizer())
+    CC1Args.push_back("-D_REENTRANT");
+}

lib/Driver/ToolChains/NetBSD.h

@@ -76,6 +76,10 @@ class LLVM_LIBRARY_VISIBILITY NetBSD : public Generic_ELF {
 
   SanitizerMask getSupportedSanitizers() const override;
 
+  void addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
+                             llvm::opt::ArgStringList &CC1Args,
+                             Action::OffloadKind DeviceOffloadKind) const override;
+
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;