Fix compiler warnings in libpixelflinger

Change-Id: I6a5708ae6bc934b196d59d81a6cd550b05ed704f
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>
diff --git a/libpixelflinger/scanline.cpp b/libpixelflinger/scanline.cpp
index aa23ca6..cd78713 100644
--- a/libpixelflinger/scanline.cpp
+++ b/libpixelflinger/scanline.cpp
@@ -534,7 +534,7 @@
     return x;
 }
 
-void blend_factor(context_t* c, pixel_t* r, 
+void blend_factor(context_t* /*c*/, pixel_t* r, 
         uint32_t factor, const pixel_t* src, const pixel_t* dst)
 {
     switch (factor) {
@@ -1161,7 +1161,7 @@
  *   blender.blend(<32-bit-src-pixel-value>,<ptr-to-16-bit-dest-pixel>)
  */
 struct blender_32to16 {
-    blender_32to16(context_t* c) { }
+    blender_32to16(context_t* /*c*/) { }
     void write(uint32_t s, uint16_t* dst) {
         if (s == 0)
             return;
@@ -1218,7 +1218,7 @@
  * where dstFactor=srcA*(1-srcA) srcFactor=srcA
  */
 struct blender_32to16_srcA {
-    blender_32to16_srcA(const context_t* c) { }
+    blender_32to16_srcA(const context_t* /*c*/) { }
     void write(uint32_t s, uint16_t* dst) {
         if (!s) {
             return;
@@ -2317,7 +2317,7 @@
     memset(dst, 0xFF, size);
 }
 
-void scanline_noop(context_t* c)
+void scanline_noop(context_t* /*c*/)
 {
 }