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/library/ecp.c b/library/ecp.c
index adef09e..796452b 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -68,13 +68,10 @@
 #define strcasecmp _stricmp
 #endif
 
-#if defined(_MSC_VER) && !defined(inline)
-#define inline _inline
-#else
-#if defined(__ARMCC_VERSION) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
-#endif /* __ARMCC_VERSION */
-#endif /*_MSC_VER */
+#endif
 
 /* Implementation that should never be optimized out by the compiler */
 static void polarssl_zeroize( void *v, size_t n ) {
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 3786356..7d26cb5 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -32,10 +32,8 @@
 
 #include <string.h>
 
-#if defined(_MSC_VER) && !defined(inline)
-#define inline _inline
-#else
-#if defined(__ARMCC_VERSION) && !defined(inline)
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
 #define inline __inline
 #endif /* __ARMCC_VERSION */
 #endif /*_MSC_VER */