use default rtlib

.travis.yml

@@ -34,7 +34,7 @@ matrix:
         CC=/usr/lib/llvm-10/bin/clang
         CXX=/usr/lib/llvm-10/bin/clang++
         CFLAGS="-O3    -Wall -Wextra -Wno-missing-field-initializers -Wno-parentheses -Wno-missing-braces -Wmissing-prototypes -Wfloat-equal -Wwrite-strings -Wpointer-arith -Wcast-align -Wnull-dereference -Werror=multichar -Werror=sizeof-pointer-memaccess -Werror=return-type -fstrict-aliasing    "
-        CXXFLAGS="-O3 -std=gnu++17    -stdlib=libc++ -rtlib=compiler-rt   -Wall -Wextra -Wno-missing-field-initializers -Wno-parentheses -Wno-missing-braces -Wno-unused-local-typedefs -Wfloat-equal -Wpointer-arith -Wcast-align -Wnull-dereference -Wnon-virtual-dtor -Wmissing-declarations -Werror=multichar -Werror=sizeof-pointer-memaccess -Werror=return-type -Werror=delete-non-virtual-dtor -fstrict-aliasing    "
+        CXXFLAGS="-O3 -std=gnu++17    -stdlib=libc++    -Wall -Wextra -Wno-missing-field-initializers -Wno-parentheses -Wno-missing-braces -Wno-unused-local-typedefs -Wfloat-equal -Wpointer-arith -Wcast-align -Wnull-dereference -Wnon-virtual-dtor -Wmissing-declarations -Werror=multichar -Werror=sizeof-pointer-memaccess -Werror=return-type -Werror=delete-non-virtual-dtor -fstrict-aliasing    "
       python: 3.6
       compiler: clang
     - os: linux