Allow to disable tapi (SDK tbd stub library helper) for bootstrapping.

--- ld64-530/src/ld/InputFiles.cpp	2020-11-23 13:30:38.000000000 -0600
+++ ld64-530/src/ld/InputFiles.cpp.notapi	2020-11-23 13:45:34.000000000 -0600
@@ -380,10 +380,12 @@
 			if ( dylibResult != NULL ) {
 				return dylibResult;
 			}
+#ifdef TAPI
 			dylibResult = textstub::dylib::parse(p, len, info.path, info.modTime, _options, info.ordinal, info.options.fBundleLoader, indirectDylib);
 			if ( dylibResult != NULL ) {
 				return dylibResult;
 			}
+#endif
 			break;
 		case Options::kStaticExecutable:
 		case Options::kDyld:
--- ld64-530/src/ld/Options.cpp	2020-11-23 13:30:38.000000000 -0600
+++ ld64-530/src/ld/Options.cpp.notapi	2020-11-23 13:44:59.000000000 -0600
@@ -34,7 +34,9 @@
 #include <spawn.h>
 #include <cxxabi.h>
 #include <Availability.h>
+#ifdef TAPI
 #include <tapi/tapi.h>
+#endif
 
 #include <vector>
 #include <map>
@@ -937,6 +939,7 @@
 bool Options::findFile(const std::string &path, const std::vector<std::string> &tbdExtensions, FileInfo& result) const
 {
 	FileInfo tbdInfo;
+#ifdef TAPI
 	for ( const auto &ext : tbdExtensions ) {
 		auto newPath = replace_extension(path, ext);
 		bool found = tbdInfo.checkFileExists(*this, newPath.c_str());
@@ -945,6 +948,7 @@
 		if ( found )
 			break;
 	}
+#endif
 
 	FileInfo dylibInfo;
 	{
@@ -957,6 +961,7 @@
 	if ( tbdInfo.missing() != dylibInfo.missing() ) {
 		result = tbdInfo.missing() ? dylibInfo : tbdInfo;
 	}
+#ifdef TAPI
 	// There are both - a text-based stub file and a dynamic library file.
 	else if ( !tbdInfo.missing() && !dylibInfo.missing() ) {
 		// Check if we should prefer the text-based stub file (env var).
@@ -978,6 +983,7 @@
 				warning("text-based stub file %s and library file %s are out of sync. Falling back to library file for linking.", tbdInfo.path, dylibInfo.path);
 			result = dylibInfo;
 		}
+#endif
 	} else {
 		return false;
 	}
@@ -4135,7 +4141,9 @@
 					fprintf(stderr, "LTO support using: %s (static support for %d, runtime is %d)\n",
 							ltoVers, lto::static_api_version(), lto::runtime_api_version());
 #endif
+#ifdef TAPI
 				fprintf(stderr, "TAPI support using: %s\n", tapi::Version::getFullVersionAsString().c_str());
+#endif
 				exit(0);
 			}
 		}
--- ld64-530/src/ld/Options.h	2019-06-14 21:33:16.000000000 -0500
+++ ld64-530/src/ld/Options.h.notapi	2020-11-23 21:24:06.000000000 -0600
@@ -28,7 +28,9 @@
 
 #include <stdint.h>
 #include <mach/machine.h>
+#ifdef TAPI
 #include <tapi/tapi.h>
+#endif
 
 #include <vector>
 #include <unordered_set>