Revert "Enable sanitizer in travis test"; ref #4864

`gcc` sanitizer does not work on some environment (namely my localhost).
Although it works on Travis, it is not convenient that tests fail on the
local host. We keep sanitizer tests on the local (using `clang`).

This reverts commit 9cde9673.

travis_config.rb

@@ -4,8 +4,7 @@ MRuby::Build.new('debug') do |conf|
 
   # include all core GEMs
   conf.gembox 'full-core'
-  conf.cc.flags += %w(-Werror=declaration-after-statement -fsanitize=address,undefined)
-  conf.linker.flags += %W(-fsanitize=address,undefined)
+  conf.cc.flags += %w(-Werror=declaration-after-statement)
   conf.compilers.each do |c|
     c.defines += %w(MRB_GC_STRESS MRB_GC_FIXED_ARENA MRB_METHOD_CACHE)
   end
@@ -19,8 +18,7 @@ MRuby::Build.new('full-debug') do |conf|
 
   # include all core GEMs
   conf.gembox 'full-core'
-  conf.cc.flags += %w(-Werror=declaration-after-statement -fsanitize=address,undefined)
-  conf.linker.flags += %W(-fsanitize=address,undefined)
+  conf.cc.flags += %w(-Werror=declaration-after-statement)
   conf.cc.defines += %w(MRB_GC_STRESS MRB_METHOD_CACHE MRB_ENABLE_DEBUG_HOOK)
 
   conf.enable_test
@@ -31,8 +29,7 @@ MRuby::Build.new do |conf|
 
   # include all core GEMs
   conf.gembox 'full-core'
-  conf.cc.flags += %w(-Werror=declaration-after-statement -fsanitize=address,undefined)
-  conf.linker.flags += %W(-fsanitize=address,undefined)
+  conf.cc.flags += %w(-Werror=declaration-after-statement)
   conf.compilers.each do |c|
     c.defines += %w(MRB_GC_FIXED_ARENA)
   end
@@ -44,8 +41,7 @@ MRuby::Build.new('cxx_abi') do |conf|
   toolchain :gcc
 
   conf.gembox 'full-core'
-  conf.cc.flags += %w(-fpermissive -fsanitize=address,undefined)
-  conf.linker.flags += %W(-fsanitize=address,undefined)
+  conf.cc.flags += %w(-fpermissive)
   conf.compilers.each do |c|
     c.defines += %w(MRB_GC_FIXED_ARENA)
   end