build: simplify clang(++) configuration

also introduce 'execClang' block

backend.native/build.gradle

@@ -105,20 +105,19 @@ String[] linkerOpts1() {
              + ["-L$libffiDir/lib", "-lffi"])
     ArrayList<String> strldflags = new ArrayList<>()
     ldflags.forEach{strldflags.add(it.toString())}
-    strldflags.add("-B$sysrootDir/usr/bin".toString())
     return strldflags.toArray(new String[0])
 }
 
 kotlinNativeInterop {
    llvm {
      defFile 'llvm.def'
-     compilerOpts "-fPIC", "-I$llvmDir/include", "-B$sysrootDir/usr/bin"
+     compilerOpts "-fPIC", "-I$llvmDir/include"
      linkerOpts linkerOpts1()
    }
 
    hash { // TODO: copy-pasted from ':common:compileHash'
      compilerOpts '-fPIC'
-     linkerOpts '-fPIC', "-B$sysrootDir/usr/bin"
+     linkerOpts '-fPIC'
      linker 'clang++'
      linkOutputs ':common:compileHash'
 

backend.native/tests/build.gradle

@@ -11,8 +11,6 @@ abstract class KonanTest extends DefaultTask {
     def backendNative = project.project(":backend.native")
     def runtimeProject = project.project(":runtime")
     def llvmLlc = llvmTool("llc")
-    def llvmC = llvmTool("clang")
-    def llvmCAdditionalArgs = ["--sysroot=$project.sysrootDir"]
     def runtimeBc = new File("${runtimeProject.buildDir.canonicalPath}/runtime.bc")
     def mainC = 'main.c'
     String goldValue = null
@@ -100,22 +98,18 @@ abstract class KonanTest extends DefaultTask {
 class UnitKonanTest extends KonanTest {
     void compileTest(File sourceS, File runtimeS, File exe) {
         def testC = sourceS.absolutePath.replace(".kt.S", "-test.c")
-        project.exec {
-            commandLine "${llvmC}", "-B${project.sysrootDir}/usr/bin", "${testC}", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
+        project.execClang {
+            commandLine "clang", "${testC}", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
                     "-o", "${exe.absolutePath}"
-
-            args llvmCAdditionalArgs
         }
     }
 }
 
 class RunKonanTest extends KonanTest {
     void compileTest(File sourceS, File runtimeS, File exe) {
-        project.exec {
-            commandLine "${llvmC}", "-DRUN_TEST", "-B${project.sysrootDir}/usr/bin", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
+        project.execClang {
+            commandLine "clang", "-DRUN_TEST", "${runtimeS.absolutePath}", "${sourceS.absolutePath}", "${mainC}", linkDl(),
                     "-o", "${exe.absolutePath}"
-
-            args llvmCAdditionalArgs
         }
     }
 }