Stop using GCC in toolchain_library

Instead, hardcode the ~dozen paths into build/soong/Android.bp, which
will unblock removing more GCC support.

Bug: 114286031
Test: m
Change-Id: I2508432e00b1469141f01e667f3c6a2fe30cd805
diff --git a/cc/cc_test.go b/cc/cc_test.go
index 3d5dfb1..01beb66 100644
--- a/cc/cc_test.go
+++ b/cc/cc_test.go
@@ -76,18 +76,21 @@
 			name: "libatomic",
 			vendor_available: true,
 			recovery_available: true,
+			src: "",
 		}
 
 		toolchain_library {
 			name: "libcompiler_rt-extras",
 			vendor_available: true,
 			recovery_available: true,
+			src: "",
 		}
 
 		toolchain_library {
 			name: "libgcc",
 			vendor_available: true,
 			recovery_available: true,
+			src: "",
 		}
 
 		cc_library {