Revert "Remove -fno-builtin to allow gcc to inline functions such as fabs, floor, creal, imag."

This reverts commit c077b9de99.

Yet another accidental commit...

newlib/libm/configure

@@ -3725,7 +3725,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/aarch64/configure

@@ -3335,7 +3335,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/arm/configure

@@ -3335,7 +3335,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/configure

@@ -3671,7 +3671,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/i386/configure

@@ -3661,7 +3661,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/nds32/configure

@@ -3358,7 +3358,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/riscv/configure

@@ -3335,7 +3335,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}
 

newlib/libm/machine/spu/configure

@@ -3335,7 +3335,7 @@ fi
 
 . ${newlib_basedir}/configure.host
 
-newlib_cflags="${newlib_cflags}"
+newlib_cflags="${newlib_cflags} -fno-builtin"
 
 NEWLIB_CFLAGS=${newlib_cflags}