Revert "bors: Fix warning list"

This reverts Rust-GCC#1585 commit 94d1116.

Conflicts:
	.github/bors_log_expected_warnings
... manually resolved and adjusted; let's see...

Author: tschwinge

.github/bors_log_expected_warnings

@@ -12,6 +12,9 @@
 ../../../libffi/src/java_raw_api.c:369:3: warning: ‘ffi_prep_java_raw_closure_loc’ is deprecated [-Wdeprecated-declarations]
 ../../../libffi/src/x86/ffi64.c:783:1: warning: label ‘out’ defined but not used [-Wunused-label]
 ../../../libffi/src/x86/ffiw64.c:250:1: warning: label ‘out’ defined but not used [-Wunused-label]
+../../c++tools/server.cc:490:11: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
+../../c++tools/server.cc:620:10: warning: ignoring return value of ‘int pipe(int*)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/../libgcc/libgcov-util.c:455:9: warning: ignoring return value of ‘int chdir(const char*)’, declared with attribute warn_unused_result [-Wunused-result]
 ../../gcc/analyzer/call-summary.cc:112:20: warning: too many arguments for format [-Wformat-extra-args]
 ../../gcc/analyzer/call-summary.cc:112:28: warning: unknown conversion type character ‘E’ in format [-Wformat=]
 ../../gcc/analyzer/call-summary.cc:114:20: warning: too many arguments for format [-Wformat-extra-args]
@@ -90,10 +93,23 @@
 ../../gcc/config/i386/i386.cc:2568:8: warning: unknown conversion type character ‘}’ in format [-Wformat=]
 ../../gcc/diagnostic.cc:2206:52: warning: format not a string literal and no format arguments [-Wformat-security]
 ../../gcc/fold-const.cc:313:42: warning: format not a string literal and no format arguments [-Wformat-security]
+../../gcc/gcc.cc:10516:12: warning: ignoring return value of ‘ssize_t read(int, void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/gcc.cc:7746:9: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/gcc.cc:7749:13: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/gcc.cc:7750:13: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/gcc.cc:7752:9: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/genhooks.cc:112:17: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/genhooks.cc:121:14: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/genhooks.cc:174:14: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/genhooks.cc:180:14: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
 ../../gcc/gimple-range-gori.cc:318:22: warning: format not a string literal and no format arguments [-Wformat-security]
 ../../gcc/ipa-devirt.cc:965:47: warning: format not a string literal and no format arguments [-Wformat-security]
+../../gcc/lto-wrapper.cc:1147:8: warning: ignoring return value of ‘ssize_t read(int, void*, size_t)’, declared with attribute warn_unused_result [-Wunused-result]
 ../../gcc/lto-wrapper.cc:1365:52: warning: format not a string literal and no format arguments [-Wformat-security]
 ../../gcc/lto-wrapper.cc:1957:44: warning: format not a string literal and no format arguments [-Wformat-security]
+../../gcc/lto/lto-common.cc:2076:10: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/lto/lto-common.cc:2078:9: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result]
+../../gcc/lto/lto-common.cc:2098:10: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
 ../../gcc/omp-low.cc:10633:19: warning: ‘T’ conversion used within a quoted sequence [-Wformat=]
 ../../gcc/omp-low.cc:1548:23: warning: ‘T’ conversion used within a quoted sequence [-Wformat=]
 ../../gcc/omp-low.cc:1553:23: warning: ‘T’ conversion used within a quoted sequence [-Wformat=]