nimble/porting: Fix OS_MEMPOOL_SIZE() macro
The OS_MEMPOOL_SIZE() macro returns an invalid
size when guards are used (an additional 4 bytes
must be reserved for each block, which is not done
at the moment). Correct this in line with the
macro defined in mynewt core.
diff --git a/porting/nimble/include/os/os_mempool.h b/porting/nimble/include/os/os_mempool.h
index 71d7706..74bc43f 100644
--- a/porting/nimble/include/os/os_mempool.h
+++ b/porting/nimble/include/os/os_mempool.h
@@ -164,7 +164,7 @@
#else
#error "Unhandled `OS_ALIGNMENT` for `os_membuf_t`"
#endif /* OS_ALIGNMENT == * */
-#define OS_MEMPOOL_SIZE(n,blksize) ((((blksize) + ((OS_ALIGNMENT)-1)) / (OS_ALIGNMENT)) * (n))
+#define OS_MEMPOOL_SIZE(n,blksize) (((OS_MEMPOOL_BLOCK_SZ(blksize) + ((OS_ALIGNMENT)-1)) / (OS_ALIGNMENT)) * (n))
/** Calculates the number of bytes required to initialize a memory pool. */
#define OS_MEMPOOL_BYTES(n,blksize) \
