[baremetal] Add atan2 to baremetal (#101767)

Co-authored-by: Petr Hosek <[email protected]>

Author: PiJoules

libc/config/baremetal/arm/entrypoints.txt

@@ -232,6 +232,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.acoshf
     libc.src.math.asinf
     libc.src.math.asinhf
+    libc.src.math.atan2
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf

libc/config/baremetal/riscv/entrypoints.txt

@@ -228,6 +228,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.acoshf
     libc.src.math.asinf
     libc.src.math.asinhf
+    libc.src.math.atan2
     libc.src.math.atan2f
     libc.src.math.atanf
     libc.src.math.atanhf