adding two empty placeholder source file required for RISCV specialization on Linux-x86_64-GCC

source/RISCV/s_bf16UIToCommonNaN.c

diff --git a/source/RISCV/s_bf16UIToCommonNaN.c b/source/RISCV/s_bf16UIToCommonNaN.c
new file mode 100644
index 0000000..861b269
--- /dev/null
+++ b/source/RISCV/s_bf16UIToCommonNaN.c
@@ -0,0 +1,5 @@
+
+/*----------------------------------------------------------------------------
+| This file intentionally contains no code.
+*----------------------------------------------------------------------------*/
+

source/RISCV/s_commonNaNToBF16UI.c

diff --git a/source/RISCV/s_commonNaNToBF16UI.c b/source/RISCV/s_commonNaNToBF16UI.c
new file mode 100644
index 0000000..861b269
--- /dev/null
+++ b/source/RISCV/s_commonNaNToBF16UI.c
@@ -0,0 +1,5 @@
+
+/*----------------------------------------------------------------------------
+| This file intentionally contains no code.
+*----------------------------------------------------------------------------*/
+