[ffigen] Work around analyzer bug for FfiNatives (#455)

* Work around analyzer bug for FfiNatives

* another pointer arg

pkgs/ffigen/example/ffinative/generated_bindings.dart

diff --git a/pkgs/ffigen/example/ffinative/generated_bindings.dart b/pkgs/ffigen/example/ffinative/generated_bindings.dart
index 794f28f..ea0436b 100644
--- a/pkgs/ffigen/example/ffinative/generated_bindings.dart
+++ b/pkgs/ffigen/example/ffinative/generated_bindings.dart
@@ -11,9 +11,9 @@
 );
 
 /// Subtracts 2 integers.
-@ffi.FfiNative<ffi.Int Function(ffi.Pointer<ffi.Int>, ffi.Int)>('subtract')
+@ffi.FfiNative<ffi.Int Function(ffi.Int, ffi.Int)>('subtract')
 external int subtract(
-  ffi.Pointer<ffi.Int> a,
+  int a,
   int b,
 );
 
@@ -32,10 +32,9 @@
 );
 
 /// Divides 2 floats, returns a pointer to double.
-@ffi.FfiNative<
-    ffi.Pointer<ffi.Double> Function(
-        ffi.Pointer<ffi.Float>, ffi.Pointer<ffi.Float>)>('dividePrecision')
+@ffi.FfiNative<ffi.Pointer<ffi.Double> Function(ffi.Float, ffi.Float)>(
+    'dividePrecision')
 external ffi.Pointer<ffi.Double> dividePrecision(
-  ffi.Pointer<ffi.Float> a,
-  ffi.Pointer<ffi.Float> b,
+  double a,
+  double b,
 );

pkgs/ffigen/example/ffinative/headers/example.h

diff --git a/pkgs/ffigen/example/ffinative/headers/example.h b/pkgs/ffigen/example/ffinative/headers/example.h
index 40c6b9e..44056dd 100644
--- a/pkgs/ffigen/example/ffinative/headers/example.h
+++ b/pkgs/ffigen/example/ffinative/headers/example.h
@@ -6,7 +6,7 @@
 int sum(int a, int b);
 
 /** Subtracts 2 integers. */
-int subtract(int *a, int b);
+int subtract(int a, int b);
 
 /** Multiplies 2 integers, returns pointer to an integer,. */
 int *multiply(int a, int b);
@@ -15,4 +15,4 @@
 float *divide(int a, int b);
 
 /** Divides 2 floats, returns a pointer to double. */
-double *dividePrecision(float *a, float *b);
+double *dividePrecision(float a, float b);