Fix macroization of inline in C++

When compiling as C++, MSVC complains about our macroization of a keyword.
Stop doing that as we know inline is always available in C++
diff --git a/include/mbedtls/cipher.h b/include/mbedtls/cipher.h
index 87d9c79..70000f5 100644
--- a/include/mbedtls/cipher.h
+++ b/include/mbedtls/cipher.h
@@ -46,7 +46,8 @@
 #define MBEDTLS_CIPHER_MODE_STREAM
 #endif
 
-#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
 #endif
 
diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index 1834b59..a70d7a6 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -27,7 +27,8 @@
 
 #include <stddef.h>
 
-#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
 #endif
 
diff --git a/include/mbedtls/pkcs11.h b/include/mbedtls/pkcs11.h
index 7632929..2e88928 100644
--- a/include/mbedtls/pkcs11.h
+++ b/include/mbedtls/pkcs11.h
@@ -37,7 +37,8 @@
 
 #include <pkcs11-helper-1.0/pkcs11h-certificate.h>
 
-#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
 #endif
 
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 73279a5..78c748c 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -41,7 +41,8 @@
 #include "sha512.h"
 #endif
 
-#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
 #endif