Add only compiler-flag dependencies as implicit

Bug: http://b/72343691

Change https://android-review.googlesource.com/c/572758, in addition to
dependencies from the compiler flags, also marked all exported
dependencies as implicit.  This can cause lots of unnecessary
recompiles.  This change moves exported dependencies back as order-only
dependencies.

Test: 1. mma in art after changing profile_compilation_info.h triggers
         only a limited number of recompiles.
      2. verify that changes to PGO profile files trigger recompiles.

Change-Id: Icb0f4cd2b6da0add3b6e5206661e6aa7a577602f
diff --git a/cc/library.go b/cc/library.go
index 00282fc..54c5476 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -384,11 +384,11 @@
 	if library.static() {
 		srcs := android.PathsForModuleSrc(ctx, library.Properties.Static.Srcs)
 		objs = objs.Append(compileObjs(ctx, buildFlags, android.DeviceStaticLibrary,
-			srcs, library.baseCompiler.pathDeps, library.baseCompiler.genDeps))
+			srcs, library.baseCompiler.pathDeps, library.baseCompiler.cFlagsDeps))
 	} else if library.shared() {
 		srcs := android.PathsForModuleSrc(ctx, library.Properties.Shared.Srcs)
 		objs = objs.Append(compileObjs(ctx, buildFlags, android.DeviceSharedLibrary,
-			srcs, library.baseCompiler.pathDeps, library.baseCompiler.genDeps))
+			srcs, library.baseCompiler.pathDeps, library.baseCompiler.cFlagsDeps))
 	}
 
 	return objs
@@ -676,8 +676,8 @@
 			}
 			library.reexportFlags(flags)
 			library.reuseExportedFlags = append(library.reuseExportedFlags, flags...)
-			library.reexportDeps(library.baseCompiler.genDeps) // TODO: restrict to aidl deps
-			library.reuseExportedDeps = append(library.reuseExportedDeps, library.baseCompiler.genDeps...)
+			library.reexportDeps(library.baseCompiler.pathDeps) // TODO: restrict to aidl deps
+			library.reuseExportedDeps = append(library.reuseExportedDeps, library.baseCompiler.pathDeps...)
 		}
 	}
 
@@ -689,8 +689,8 @@
 			}
 			library.reexportFlags(flags)
 			library.reuseExportedFlags = append(library.reuseExportedFlags, flags...)
-			library.reexportDeps(library.baseCompiler.genDeps) // TODO: restrict to proto deps
-			library.reuseExportedDeps = append(library.reuseExportedDeps, library.baseCompiler.genDeps...)
+			library.reexportDeps(library.baseCompiler.pathDeps) // TODO: restrict to proto deps
+			library.reuseExportedDeps = append(library.reuseExportedDeps, library.baseCompiler.pathDeps...)
 		}
 	}