Create libgfx, starting with FloatRect

Creates libgfx, the future home of everything currently in libui and
libgui, which will be rigorously checked with -Weverything (with a few
common-sense exceptions) and clang-tidy and formatted using the included
.clang-format file.

Starts by moving FloatRect out of services/surfaceflinger since it will
be used by other libgfx primitives later.

Test: m
Change-Id: I5045ac089020e6ee380e81e8735117c500264b37
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h b/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h
index 170e382..bca25ac 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h
@@ -48,12 +48,14 @@
 // ---------------------------------------------------------------------------
 
 class Fence;
-class FloatRect;
 class GraphicBuffer;
 class NativeHandle;
 class Region;
 class String8;
 class SurfaceFlinger;
+namespace gfx {
+    class FloatRect;
+}
 
 class HWComposer
 {
@@ -168,7 +170,7 @@
         virtual void setBlending(uint32_t blending) = 0;
         virtual void setTransform(uint32_t transform) = 0;
         virtual void setFrame(const Rect& frame) = 0;
-        virtual void setCrop(const FloatRect& crop) = 0;
+        virtual void setCrop(const gfx::FloatRect& crop) = 0;
         virtual void setVisibleRegionScreen(const Region& reg) = 0;
         virtual void setSurfaceDamage(const Region& reg) = 0;
         virtual void setSidebandStream(const sp<NativeHandle>& stream) = 0;