azpainter: fix build

the configure script was erasing the enviroment's compiler/cflags
setting, which resulted in broken builds with ccache enabled - this
is because with ccache we have a bunch of symlinks installed, one
of which is clang, and the configure script's autodetection first
checks for clang and then for gcc

however, there is no actual clang installed, and their check is
wrong, as it uses 'type' rather than 'command' and the former
will also succeed for broken symlinks (as it only checks the
existence of the path, regardless of if it's broken or not)

that said, even with ccache off, this would still build wrong,
since it would be ignoring the compiler flags on native builds,
and additionally the cross-compiling environment on cross builds

srcpkgs/azpainter/patches/fix-compiler-environment.patch

@@ -0,0 +1,18 @@
+--- configure
++++ configure
+@@ -150,10 +150,11 @@ fc_check_command_err sed
+ #-------------
+ # option
+ 
+-CC=
+-CFLAGS=
+-LDFLAGS=
+-LIBS=
++# sketchy nonsense overriding our environment
++#CC=
++#CFLAGS=
++#LDFLAGS=
++#LIBS=
+ 
+ CFLAGS_ADD=
+ LDFLAGS_ADD=