BUG #17160: PostgreSQL13.4:Build failure with GNU Compiler.

The following bug has been logged on the website:

Bug reference:      17160
Logged by:          arjun shetty
Email address:      arjunshetty955@gmail.com
PostgreSQL version: 13.4
Operating system:   Ubuntu 20.04.1 LTS
Description:        

Observed build errors on PostgreSQLv13.4/PostgreSQLv14beta2 with GNU
Compiler.

GCC Build Command: 
CC=gcc CXX=g++ ../configure --prefix= CFLAGS='-O3
-march=native -flto' CXXFLAGS='-O3 -march=native -flto'
build errror:
/tmp/zic.soWwyC.ltrans0.ltrans.o::(.text.startup+0xf7b): more
undefined references to `pg_fprintf' follow
/tmp/zic.soWwyC.ltrans0.ltrans.o: In function `main':
:(.text.startup+0xfe9): undefined reference to `pg_strerror'
:(.text.startup+0x1009): undefined reference to `pg_fprintf'
collect2: error: ld returned 1 exit status
make[2]: *** [Makefile:55: zic] Error 1

without  flto build was success 
-flto=thin supported for clang(llvm) .
GCC supports LTO(can use normal flto or GCC has an equivalent to Thin LTO:
WHOle Program optimizeR (WHOPR) i.e like -flto=fwhopr )