Extract default build env to unix shell

src/SPC/builder/unix/library/gmp.php

@@ -15,15 +15,14 @@ trait gmp
      */
     protected function build(): void
     {
-        shell()->cd($this->source_dir)
-            ->setEnv(['CFLAGS' => $this->getLibExtraCFlags() ?: $this->builder->arch_c_flags, 'LDFLAGS' => $this->getLibExtraLdFlags(), 'LIBS' => $this->getLibExtraLibs()])
-            ->execWithEnv(
+        shell()->cd($this->source_dir)->initLibBuildEnv($this)
+            ->exec(
                 './configure ' .
                 '--enable-static --disable-shared ' .
                 '--prefix='
             )
-            ->execWithEnv('make clean')
-            ->execWithEnv("make -j{$this->builder->concurrency}")
+            ->exec('make clean')
+            ->exec("make -j{$this->builder->concurrency}")
             ->exec('make install DESTDIR=' . BUILD_ROOT_PATH);
         $this->patchPkgconfPrefix(['gmp.pc']);
     }