Fix strict aliasing violation from conditional typedef of wchar_t by building entire project as C++ for Unix (#6801)

Enable building CoreCLR as C++ project on Unix

This series of patches fixes the strict aliasing violation from
the conditional typedef of wchar_t in src/pal/inc/pal_char16.h:40

* rename c files to cpp
* modify all cmake files to change .c files to .cpp
* apply c++ linkage to templates

19 files changed, 2 insertions, 4 deletions

diff --git a/src/pal/prebuilt/idl/clrdata_i.c b/src/pal/prebuilt/idl/clrdata_i.cpp
index bb9616a9f8..bb9616a9f8 100644
--- a/src/pal/prebuilt/idl/clrdata_i.c
+++ b/src/pal/prebuilt/idl/clrdata_i.cpp
diff --git a/src/pal/prebuilt/idl/clrinternal_i.c b/src/pal/prebuilt/idl/clrinternal_i.cpp
index 58a16672cf..58a16672cf 100644
--- a/src/pal/prebuilt/idl/clrinternal_i.c
+++ b/src/pal/prebuilt/idl/clrinternal_i.cpp
diff --git a/src/pal/prebuilt/idl/clrprivappxhosting_i.c b/src/pal/prebuilt/idl/clrprivappxhosting_i.cpp
index c46d033d1a..c46d033d1a 100644
--- a/src/pal/prebuilt/idl/clrprivappxhosting_i.c
+++ b/src/pal/prebuilt/idl/clrprivappxhosting_i.cpp
diff --git a/src/pal/prebuilt/idl/clrprivbinding_i.c b/src/pal/prebuilt/idl/clrprivbinding_i.cpp
index ee08cc3583..ee08cc3583 100644
--- a/src/pal/prebuilt/idl/clrprivbinding_i.c
+++ b/src/pal/prebuilt/idl/clrprivbinding_i.cpp
diff --git a/src/pal/prebuilt/idl/clrprivhosting_i.c b/src/pal/prebuilt/idl/clrprivhosting_i.cpp
index 07a40b290e..07a40b290e 100644
--- a/src/pal/prebuilt/idl/clrprivhosting_i.c
+++ b/src/pal/prebuilt/idl/clrprivhosting_i.cpp
diff --git a/src/pal/prebuilt/idl/clrprivruntimebinders_i.c b/src/pal/prebuilt/idl/clrprivruntimebinders_i.cpp
index 0fe4a180df..0fe4a180df 100644
--- a/src/pal/prebuilt/idl/clrprivruntimebinders_i.c
+++ b/src/pal/prebuilt/idl/clrprivruntimebinders_i.cpp
diff --git a/src/pal/prebuilt/idl/cordebug_i.c b/src/pal/prebuilt/idl/cordebug_i.cpp
index e3c8d2edcb..e3c8d2edcb 100644
--- a/src/pal/prebuilt/idl/cordebug_i.c
+++ b/src/pal/prebuilt/idl/cordebug_i.cpp
diff --git a/src/pal/prebuilt/idl/corprof_i.c b/src/pal/prebuilt/idl/corprof_i.cpp
index 4686c76d54..4686c76d54 100644
--- a/src/pal/prebuilt/idl/corprof_i.c
+++ b/src/pal/prebuilt/idl/corprof_i.cpp
diff --git a/src/pal/prebuilt/idl/corpub_i.c b/src/pal/prebuilt/idl/corpub_i.cpp
index 982f89724e..982f89724e 100644
--- a/src/pal/prebuilt/idl/corpub_i.c
+++ b/src/pal/prebuilt/idl/corpub_i.cpp
diff --git a/src/pal/prebuilt/idl/corsym_i.c b/src/pal/prebuilt/idl/corsym_i.cpp
index 7ef9242315..7ef9242315 100644
--- a/src/pal/prebuilt/idl/corsym_i.c
+++ b/src/pal/prebuilt/idl/corsym_i.cpp
diff --git a/src/pal/prebuilt/idl/fusionpriv_i.c b/src/pal/prebuilt/idl/fusionpriv_i.cpp
index ece9622114..ece9622114 100644
--- a/src/pal/prebuilt/idl/fusionpriv_i.c
+++ b/src/pal/prebuilt/idl/fusionpriv_i.cpp
diff --git a/src/pal/prebuilt/idl/gchost_i.c b/src/pal/prebuilt/idl/gchost_i.cpp
index 32ecfbe9d5..32ecfbe9d5 100644
--- a/src/pal/prebuilt/idl/gchost_i.c
+++ b/src/pal/prebuilt/idl/gchost_i.cpp
diff --git a/src/pal/prebuilt/idl/ivalidator_i.c b/src/pal/prebuilt/idl/ivalidator_i.cpp
index 0edbec448a..0edbec448a 100644
--- a/src/pal/prebuilt/idl/ivalidator_i.c
+++ b/src/pal/prebuilt/idl/ivalidator_i.cpp
diff --git a/src/pal/prebuilt/idl/ivehandler_i.c b/src/pal/prebuilt/idl/ivehandler_i.cpp
index 44d0b961bb..44d0b961bb 100644
--- a/src/pal/prebuilt/idl/ivehandler_i.c
+++ b/src/pal/prebuilt/idl/ivehandler_i.cpp
diff --git a/src/pal/prebuilt/idl/mscorsvc_i.c b/src/pal/prebuilt/idl/mscorsvc_i.cpp
index 05d04e58a6..05d04e58a6 100644
--- a/src/pal/prebuilt/idl/mscorsvc_i.c
+++ b/src/pal/prebuilt/idl/mscorsvc_i.cpp
diff --git a/src/pal/prebuilt/idl/sospriv_i.c b/src/pal/prebuilt/idl/sospriv_i.cpp
index 7fee909ca3..3584b761d2 100644
--- a/src/pal/prebuilt/idl/sospriv_i.c
+++ b/src/pal/prebuilt/idl/sospriv_i.cpp
@@ -20,15 +20,13 @@
 
 #pragma warning( disable: 4049 )  /* more than 64k source lines */
 
+#include <rpc.h>
+#include <rpcndr.h>
 
 #ifdef __cplusplus
 extern "C"{
 #endif 
 
-
-#include <rpc.h>
-#include <rpcndr.h>
-
 #ifdef _MIDL_USE_GUIDDEF_
 
 #ifndef INITGUID
diff --git a/src/pal/prebuilt/idl/tlbimpexp_i.c b/src/pal/prebuilt/idl/tlbimpexp_i.cpp
index 0eb2791fa3..0eb2791fa3 100644
--- a/src/pal/prebuilt/idl/tlbimpexp_i.c
+++ b/src/pal/prebuilt/idl/tlbimpexp_i.cpp
diff --git a/src/pal/prebuilt/idl/xclrdata_i.c b/src/pal/prebuilt/idl/xclrdata_i.cpp
index 6dd642da4c..6dd642da4c 100644
--- a/src/pal/prebuilt/idl/xclrdata_i.c
+++ b/src/pal/prebuilt/idl/xclrdata_i.cpp
diff --git a/src/pal/prebuilt/idl/xcordebug_i.c b/src/pal/prebuilt/idl/xcordebug_i.cpp
index a3d9395530..a3d9395530 100644
--- a/src/pal/prebuilt/idl/xcordebug_i.c
+++ b/src/pal/prebuilt/idl/xcordebug_i.cpp